1. Introduction:
Open Source Software (OSS) is software whose source code is openly published, which is
usually available at no charge, and which is often developed by voluntary efforts. OSS has leapt
to prominence by starting to take a significant market share in some specific parts of the software
infrastructure market. For example, since 1998 Linux has been one of the fastest growing
servers’ operating systems. Indeed, in a few important market segments, such as storing Web
Pages, OSS software is far and away the market leader.
The software industry is very fast moving, and frequently throws up promising new
developments that initially promise to make great changes in the marketplace, but which
ultimately fail to live up to their initial press hype. Our first key conclusion is that OSS is indeed
the start of a fundamental change in the software infrastructure marketplace, and is not a hype
bubble that will burst. This is perhaps surprising because OSS does at first sight appear to be a
bit of a paradox.
Given that OSS software is often developed by largely volunteer efforts, how can software, such
as the Linux operating system, compete with software such as Microsoft Windows, which has
had, and will continue to have, billions of dollars invested in it? In particular, how is it that the
best OSS is perceived by many to be at least as reliable as market leading proprietary software?
The body of this paper explains how this has happened. OSS’s credibility has been established as
market giants such as HP, IBM and Sun have thrown their weight behind it.
Open-source software (OSS) is computer software with its source code made available and
licensed with a license in which the copyright holder provides the rights to study, change and
distribute the software to anyone and for any purpose. Open-source software is very often
developed in a public, collaborative manner. Open-source software is the most prominent
example of open-source development and often compared to (technically defined) user-generated
content or (legally defined) open-content movements.

2. There is a great interest in open source software. Prospective purchasers all over the world find
themselves in a situation much like that which we see in Swedish public administration, and
developing countries cannot afford to buy software at the current price levels of the major
suppliers. In many countries, priority is instead given to resources for developing an IT
infrastructure and for creating electronic services for citizens.
Open source software has been such a growing trend over the past few years that it has turned
into a buzzword within the information technology industry. In many cases, some confusion has
grown as to what it means to say something is open source, and why such software exists. In this
assignment we will try to dispel some of this confusion and discuss the potential benefits of open
source tools and components as well as the (sometimes) hidden pitfalls to avoid. Special
consideration will be given to considering the use of open source tools in a mission critical
manufacturing setting, and we offer a simple risk graphing tool that can be used in evaluating
software.
While the term "open source" applied originally only to the source code of software, it is now
being applied to many other areas such as Open source ecology, a movement to decentralize
technologies so that any human can use them. However, it is often misapplied to other areas
which have different and competing principles, which overlap only partially.
Definition:
The Open Source Initiative's definition is widely recognized as the standard or de
facto definition. Eric.S.Raymond and Bruce Perens formed the organization in February 1998.
With about 20 years of evidence from case histories of closed and open development already
provided by the Internet, OSI {Open Source Initiative} continued to present the "open source"
case to commercial businesses. They sought to bring a higher profile to the practical benefits of
freely available source code, and wanted to bring major software businesses and other high-tech
industries into open source.
OSI uses The Open Source Definition to determine whether it considers a software license open
source. The definition was based on the Debian Free Software Guidelines, written and adapted
primarily by Perens. Perens did not base his writing on the "four freedoms" of Free Software
from the FSF, which were only widely available later.

3. Under Perens' definition, open source describes a broad general type of software license that
makes source code available to the general public with relaxed or non-existent copyright
restrictions. The principles, as stated, say absolutely nothing about trademark or patent use and
require absolutely no cooperation to ensure that any common audit or release regime applies to
any derived works. It is an explicit "feature" of open source that it may put no restrictions on the
use or distribution by any organization or user. It forbids this, in principle, to guarantee
continued access to derived works even by the major original contributors.
However, Richard Stallman of the Free Software Foundation flatly opposes the term "Open
Source" being applied to what they refer to as "free software". Although it is clear that legally
free software does qualify as open source, Stallman considers that the category is abusive. Critics
also oppose the professed pragmatism of the Open Source Initiative, as they fear that the free
software ideals of freedom and community are threatened by compromising on the FSF's
idealistic standards for software freedom.
Open source software has traditionally meant that the uncompelled source code has been
published to the general public with an acceptance of some license agreement. Some examples of
these are GNU Public License (GPL), Berkely Software Distribution (BSD) and Lesser GNU
Public License (LGPL). These agreements allow you to download the software source code,
compile it, modify it, and possibly sell it as long as you provide a means for the original source
code to be retrieved. While open source in many people's minds means free, there are even some
companies now shipping the source code with their purchased products open source doesn't
mean just free software.
Open specification means that there is a published document that describes how to build a piece
of software. The most common example of a specification is standards development. The
standard is documented and you can read it. An open specification is one that is freely available
to anyone who wants a copy, without cost or membership requirements. A good example of an
open specification is the World Batch Federation xml schema. The document has been published
with a license that allows anyone to read it and use in for development.

4. Open API (Application Program Interface) means that sufficient documentation is supplied with
a software package to allow a programmer to use it in other code s/he is writing. Open API's are
common with software libraries where you purchase code that is intended to be used within your
developed code. An example of this would be purchasing a collection of graphical interface
beans (temperature and pressure gauges, dials and scales) to be used in one or more applets that
are the user interface to equipment controls. You may not have received the source code for the
temperature gauge bean, but you get documentation on how to use the bean, and what interfaces
and connections are available with this bean.
Companies that develop software under the open source model are gaining the benefit of having
a mass of talented people working for them for the right to develop/ tinker with the source code.
A couple of examples of this are the Mozilla project sponsored by Netscape and Netbeans
sponsored by Sun Microsystems. Both of these companies use the open source implementation
as the core of their supported product. The benefit to them is that they acquire the innovation of
new development that works within a common framework that they have based their product on.
This reduces the cost of developing new features and increases the robustness of the software
due to the sheer number of people using the tool and developers fixing the bugs.
Why do people make open source software?
There is no simple answer for why highly talented programmers work to develop open source
software. Those who are developing open source software which is for resale often quote a belief
in the "goodness" of sharing source code, as well as lowered costs for their development and an
expanded development staff. It has become very common for many companies to use the open
source process for R&D, allowing the market pressures and interests of the global programming
community to guide and power their new development activities without the overhead of hiring a
development team. The motivations of someone writing software they intend to give away for
free are often unclear. The core motivations are, being recognized as being great programmers by
their peers, seeing a need for a particular tool, or the challenge of a new idea. For example
Apache is a well known web server and has surpassed many on the commercial servers in

5. popularity. With this growth in popularity, some businesses are backing the apache foundation
with resources to continue to develop, support and maintain the software.
Issues and Considerations
While the term "open source" applied originally only to the source code of software, it is now
being applied to many other area such as Open source ecology, a movement to decentralize
technologies so that any human can use them. However, it is often misapplied to other areas
which have different and competing principles, which overlap only partially.
In 1997, Eric Raymond published The Cathedral and the Bazaar, a reflective analysis of the
hacker community and free software principles. The paper received significant attention in early
1998, and was one factor in motivating Netscape Communications Corporation to release their
popular Netscape Communicator Internet suite as free software. This code is today better known
as Mozilla Firefox and Thunderbird.
Netscape's act prompted Raymond and others to look into how to bring the FSF's free software
ideas and perceived benefits to the commercial software industry. They concluded that FSF's
social activism was not appealing to companies like Netscape, and looked for a way to rebrand
the free software movement to emphasize the business potential of sharing and collaborating on
software source code. The new name they chose was "open source", and quickly Bruce Perens,
publisher Tim O'Reilly, Linus Torvalds, and others signed on to the rebranding. The Open
Source Initiative was founded in February 1998 to encourage use of the new term and evangelize
open-source principles.
While the Open Source Initiative sought to encourage the use of the new term and evangelize the
principles it adhered to, commercial software vendors found themselves increasingly threatened
by the concept of freely distributed software and universal access to an application's source code.
A Microsoft executive publicly stated in 2001 that "open source is an intellectual property
destroyer. I can't imagine something that could be worse than this for the software business and
the intellectual-property business." This view perfectly summarizes the initial response to FOSS
by some software corporations. However, while FOSS has historically played a role outside of
the mainstream of private software development, companies as large as Microsoft have begun to

6. develop official open-source presences on the Internet. IBM, Oracle, Google and State Farm are
just a few of the companies with a serious public stake in today's competitive open-
source market. There has been a significant shift in the corporate philosophy concerning the
development of free and open-source software (FOSS).
The Open Source Definition, notably, presents an open-source philosophy, and further defines
the terms of usage, modification and redistribution of open-source software. Software licenses
grant rights to users which would otherwise be reserved by copyright law to the copyright holder.
Several open-source software licenses have qualified within the boundaries of the Open Source
Definition. The most prominent and popular example is the GNU General Public License (GPL),
which "allows free distribution under the condition that further developments and applications
are put under the same license", thus also free. While open-source distribution presents a way to
make the source code of a product publicly accessible, the open-source licenses allow the authors
to fine tune such access.
Many people claimed that the birth of the Internet, since 1969, started the open source
movement, while others do not distinguish between open-source and free software movements.
The Open Source Initiative (OSI) was formed in February 1998 by Eric S. Raymond and Bruce
Perens. With at least 20 years of evidence from case histories of closed software development
versus open development already provided by the Internet developer community, the OSI
presented the "open source" case to commercial businesses, like Netscape. The OSI hoped that
the usage of the label "open source", a term suggested by Peterson of the Foresight Institute at
the strategy session, would eliminate ambiguity, particularly for individuals who perceive "free
software" as anti-commercial. They sought to bring a higher profile to the practical benefits of
freely available source code, and they wanted to bring major software businesses and other high-
tech industries into open source. Perens attempted to register "open source" as a service mark for
the OSI, but that attempt was impractical by trademark standards. Meanwhile, due to the
presentation of Raymond's paper to the upper management at Netscape—Raymond only
discovered when he read the Press Release and was called by Netscape CEO Jim Barksdale's PA
later in the day—Netscape released its Navigator source code as open source, with favorable
results.

7. Integration Issues:
Another big potential for manufacturing IT is that open source tools lend themselves to easier
integration than a tool with a proprietary API. Why is it easier? This is a complex question that is
tied to issues of flexibility, code understandability and response of the user/developer
communities.
Flexibility:
The main advantage here is that you have access to the source code and can extend it as needed
to fit your environment. If a needed link into other systems does not exist, you can build it. If a
function is not fully comprehensive of your internal processes, you can edit the function code
and make it match your internal needs. This tends to help reduce the cost of an integration
project. The pitfall to avoid here is modification of the core software of the package. This type of
modification means that you must support this modification for each upgrade of the system. This
is the same pitfall you would face with upgrades of non-open source tools. The advantage here is
that if you participate in the community you may get your changes integrated in to the software
product.
Understandability:
Open source software tends to have more comprehensive documentation. In most cases, just like
the source code being editable, the documentation is also editable. Lots of people have read it,
had input to it, made changes, and there tends to be MORE documentation of how the tool
actually works. The application also tends to be documented to a detail level for someone who
may even want to work on the source code, and makes no assumptions about what you do or do
not need to know. If you are not a technical user, this can sometimes mean that the
documentation is overwhelming or a little harder to find.
User Communities:
If you have ever waited for a phone or email response back from an application support staff,
you know how frustrating and potentially expensive this wait can be. Although a few open
source tools have support you can also purchase, most are supported by newsgroups and/or
mailing lists for users and /or developers. Be sure the tool you choose has an active user support
community these are actually often more responsive than phone support and you can often get

8. fast replies and help in your troubleshooting. Not all tools have an active user community, so
check this out. If there is no user community, be sure you have staff that understand the tool and
are cross training several people, so you are not stuck when your one guru goes on vacation, or
leaves the company. Staff might need to troubleshoot this tool. This gives them quick access to
the answers they need to get production back on line at 3am.
Flexibility and Extensibility:
We have already partly addressed the advantages of the flexibility of open source software in the
above section on integration issues, but the flexibility of open source software continues to have
an impact beyond integration. The obvious advantage here is in both cost and time, because you
can twiddle the code, you do not have to pay the company or wait for their timeline to make the
modifications you need to run your business. Using Open Source software in manufacturing
systems also gives you the ability to grow the software and the system as your business needs
grow and change, rather than replacing the entire system. With careful system design and some
forethought, you can build a system with open source tools that allows your business to grow its
infrastructure at the rate it needs. Rather than spending 3million dollars for a full-featured MES,
when all you really need/ want is a WIP tracking system that allows routing, you can implement
the minimal solution with tools that allow you to grow the feature set. Flexibility and
extensibility over a long period of time are more characteristics of a good design than of any
particular software characteristics.
Open-source software development:
In his 1997 essay The Cathedral and the Bazaar, open-source evangelist Eric S.
Raymond suggests a model for developing OSS known as the bazaar model. Raymond likens the
development of software by traditional methodologies to building a cathedral, "carefully crafted
by individual wizards or small bands of mages working in splendid isolation". He suggests that
all software should be developed using the bazaar style, which he described as "a great babbling
bazaar of differing agendas and approaches."
In the traditional model of development, which he called the cathedral model; development takes
place in a centralized way. Roles are clearly defined. Roles include people dedicated to designing

9. (the architects), people responsible for managing the project, and people responsible for
implementation. Traditional software engineering follows the cathedral model. Fred P. Brooks in
his book The Mythical Man-Month advocates this model. He goes further to say that in order to
preserve the architectural integrity of a system; the system design should be done by as few
architects as possible. The bazaar model, however, is different. In this model, roles are not
clearly defined. Gregorio Robles suggests that software developed using the bazaar model should
exhibit the following patterns:
Users should be treated as co-developers:
The users are treated like co-developers and so they should have access to the source code of the
software. Furthermore users are encouraged to submit additions to the software, code fixes for
the software, bug reports, documentation etc. Having more co-developers increases the rate at
which the software evolves. Linux's law states, "Given enough eyeballs all bugs are shallow."
This means that if many users view the source code, they will eventually find all bugs and
suggest how to fix them. Note that some users have advanced programming skills, and
furthermore, each user's machine provides an additional testing environment. This new testing
environment offers that ability to find and fix a new bug.
Early releases:
The first version of the software should be released as early as possible so as to increase one's
chances of finding co-developers early.
Frequent integration:
Code changes should be integrated (merged into a shared code base) as often as possible so as to
avoid the overhead of fixing a large number of bugs at the end of the project life cycle. Some
open source projects have nightly builds where integration is done automatically on a daily basis.
Several versions:
There should be at least two versions of the software. There should be a buggier version with
more features and a more stable version with fewer features. The buggy version (also called the
development version) is for users who want the immediate use of the latest features, and are

10. willing to accept the risk of using code that is not yet thoroughly tested. The users can then act as
co-developers, reporting bugs and providing bug fixes.
High modularization:
The general structure of the software should be modular allowing for parallel development on
independent components.
Dynamic decision making structure:
There is a need for a decision making structure, whether formal or informal, that makes strategic
decisions depending on changing user requirements and other factors. Cf. Extreme programming.
Data suggests, however, that OSS is not quite as democratic as the bazaar model suggests. An
analysis of five billion bytes of free/open source code by 31,999 developers shows that 74% of
the code was written by the most active 10% of authors. The average number of authors involved
in a project was 5.1, with the median at 2.
Considerations for software producers:
Software experts and researchers on open source software have identified several advantages and
disadvantages. The main advantage for business is that open source is a good way for business to
achieve greater penetration of the market. Companies that offer open source software are able to
establish an industry standard and, thus, gain competitive advantage. It has also helped build
developer loyalty as developers feel empowered and have a sense of ownership of the end
product.
Moreover, lower costs of marketing and logistical services are needed for OSS. OSS also helps
companies keep abreast of technology developments. It is a good tool to promote a company's
image, including its commercial products. The OSS development approach has helped produce
reliable, high quality software quickly and inexpensively.
Not all OSS initiatives have been successful, for example Source exchange and Eazel. Software
experts and researchers who are not convinced by open source's ability to produce quality
systems identify the unclear process, the late defect discovery and the lack of any empirical
evidence as the most important problems (collected data concerning productivity and quality). It
is also difficult to design a commercially sound business model around the open source

11. paradigm. Consequently, only technical requirements may be satisfied and not the ones of the
market. In terms of security, open source may allow hackers to know about the weaknesses or
loopholes of the software more easily than closed-source software. It depends on control
mechanisms in order to create effective performance of autonomous agents who participate in
virtual organizations.
Development tools:
In OSS development, the participants, who are mostly volunteers, are distributed among different
geographic regions, so there is need for tools to aid participants to collaborate in source code
development. Often, these tools are also available as OSS.
Revision control systems such as Concurrent Versions System (CVS) and
later Subversion (SVN) and Git, and the GNU Compiler Collection are examples of tools that
help centrally manage the source code files and the changes to those files for a software project.
These tools are themselves OSS.
Utilities that automate testing, compiling, and bug reporting help preserve stability and support
of software projects that have numerous developers but no managers, quality controller, or
technical support. Building systems that report compilation errors among different platforms
include Tinderbox. Commonly used bug trackers include Bugzilla and GNATS.
Tools such as mailing lists, IRC, and instant messaging provide means of Internet
communication between developers. The Web is also a core feature of all of the above systems.
Some sites centralize all the features of these tools as a software development management
system, including GNU Savannah, Source Forge, and Bounty Source.
Potential Impacts
Where will it all ends? We now have to move into the area of predictions. Within five years,
50% of the volume of the software infrastructure market could be taken by OSS. We expect that
OSS's position in the small server market (file and print servers and Web servers) will grow
fastest. OSS's position in large servers (e.g. those managing massive multi-user databases), such
as those that underpin many large Government procurements, will grow from its current position

12. of near zero penetration, to a position where OSS is a viable option, within 2 - 3 years. Within
the developed world, we as yet see no sign that OSS will become a viable alternative to
Microsoft Windows, for users’ (general purpose) desktop machines in the corporate or home PC
markets. However, OSS on the desktop may soon become a significant player on the desktop in
the developing world. For these reasons the study recommends against any preference for OSS
on the desktop, but also recommends that this issue be reassessed by the end of 2002, by which
time early trials of the use of OSS desktops may have generated sufficient evidence to warrant a
reassessment.
OSS is already suited to restricted functionality desktops, such as those used in industry for
point-of-sales and point-of-service terminals; and in these areas OSS’s market share is likely to
grow significantly. We expect OSS to rapidly become the market leader in consumer computing
devices. We expect the market for new portable and consumer computing devices (such as set
top boxes and smart mobile phones) to remain very dynamic, with no dominant market leader
emerging. OSS is however likely to be a significant player in this market. We expect that the
software infrastructure that is implemented on top of operating systems (so-called middleware)
will move gradually from proprietary products towards OSS.
All of the above predictions relate to the software infrastructure market. As yet, it is not possible
to predict that, within the developed world, OSS will make such a major contribution to the
software applications market. There are a few OSS applications that are becoming significant,
but it is too early to say if a trend is developing.
An essential element of the digital commons is open source software, such as Linux, Apache,
MySQL, PHP, JavaScript, and Wordpress. The authors of The Economic Impact of Open Source
on Small Business describe how "like the ecosystem services provided by the sun, the open
source software that makes the web possible disappears from our accounting."
This 50 page Radar Report from O'Reilly Media is appropriately open source at £0.00 – so there
are no excuses not to have a quick browse. The book attempts to speak up for the developers of
open source software projects and the communities that support them – the "unsung heroes of the
economy"- by placing an economic value on their work product.

13. The majority of the report is a comprehensive survey of the ISP's customers, detailing how
SMBs use ISP services in their business model and the technologies they employ, with simple
graphical representations of the data.
The authors lay out their assumptions and work up a model to estimate that businesses that rely
on hosting/domain name providers for their web presence represent a trillion dollar market. Two
case studies look at return on investment scenarios, including some surprising assumptions
regarding the profitability of Search Engine Optimization and Google Edwards. The report
concludes with an analysis of programming language trends.
The dividing line between where open source is appropriate and where it is not is the distinction
between software that is generic infrastructure versus that which is essential (unique) to the very
nature of the business itself. Open source has or can have an important role to play in the
infrastructure arena but will never, as long as the world's economy is dominated by market
processes, play any significant role in those areas that are central to the unique characteristics of
commercial organizations and allow one company to differentiate itself from another or gain a
strategic competitive advantage in its market area.
Open source terrorizes Microsoft, not because it's inherently anti-business, but because
Microsoft's entire software line is purely infrastructure and thus the natural territory of open
source. Immediately Linux threatens Windows and Apache is IIS's largest obstacle. In the long
run, there is an already existing open source competitor to most Microsoft products though most
are not as developed as Linux or Apache.
Open source theoretically threatens the entire software industry as it exists today. By "software
industry" I'm thinking every company that sells (licenses) largely the same software to two or
more customers. This potentially includes all companies that sell true commodity shrink-wrap
software to shareware to vertical market consulting firms that sell "packages" that are source
code modified for each customer. If more than one company uses a product, then that product is
not unique to any company and starts to look like my loose definition of infrastructure. Extensive
customizations unique to a customer start to move closer to core business processes. If however,
the developer retains ownership of the code, and is free to add any good ideas they get from one
customer to common code sold to any future customers, then it's not unique or at least not
anymore.

14. The theoretical threat is greatly reduced by practical obstacles to open source. Generally this is
the high cost of developing new high quality software. Where a project can start small and grow
incrementally over time, the open source model is likely to work well. Where a product is needed
quickly with a very high level of functionality from day one, it's hard to see how open source can
solve the problem except where a mechanism exists to coordinate the potential beneficiaries.
Over a long period of time, dedicated programmers may contribute large amounts of time to an
open source project. With one exception, I've never heard of anyone putting significant sums of
money into a new product, software or otherwise, for the purpose of giving it away. Whether it's
a large software company investing its development dollars in a new product or a couple of
programmers using their life savings to start a new company, if the product is highly marketable,
anyone with a trace of business sense knows the real profits are to be made in license fees, not
service and support. This is especially true of low priced, simple products, aimed at a mass
market. As products become more complex (and expensive) the opportunity for service and
support fees increase as well.
Conclusion
The term "open source" was originally intended to be trademarkable; however, the term was
deemed too descriptive, so no trademark exists. Besides, it offers the potential for a more flexible
technology and quicker innovation. It is said to be more reliable since it typically has thousands
of independent programmers testing and fixing bugs of the software. It is flexible because
modular systems allow programmers to build custom interfaces, or add new abilities to it and it
is innovative since open source programs are the product of collaboration among a large number
of different programmers. The mix of divergent perspectives, corporate objectives, and personal
goals speeds up innovation.
Moreover, free software can be developed in accord with purely technical requirements. It does
not require thinking about commercial pressure that often degrades the quality of the software.
Commercial pressures make traditional software developers pay more attention to customers'
requirements than to security requirements, since such features are somewhat invisible to the
customer. It is sometimes said that the open source development process may not be well

15. defined and the stages in the development process, such as system testing and documentation
may be ignored. However this is only true for small (mostly single programmer) projects. Larger,
successful projects do define and enforce at least some rules as they need them to make the
teamwork possible. In the most complex projects these rules may be as strict as reviewing even
minor change by two independent developers.
"We migrated key functions from Windows to Linux because we needed an operating system
that was stable and reliable - one that would give us in-house control. So if we needed to patch,
adjust, or adapt, we could."
Open standards and formats along with free and open source software are important factors in
order to be able to arrive at:
- increased competetivity
- improved interoperability
- reduced costs
For administration in the public sector. Open source software is not any makeshift phenomenon,
but instead a fully adequate and dependable competitor to existing proprietary products and
solutions. In summary we feel that open source tools are a good fit in the manufacturing setting,
even in mission critical systems, as long as you follow the following rules of thumb:
1) Do a careful Risk analysis
2) Have a good support plan/staff in place
3) Support the tools and their communities
4) Understand the capabilities or limitations of your developers.
5) Have a good system design to allow for growth and flexibility.
It is undoubtedly correct to assert that there are several benefits in using open source software in
a commercial context. It can guarantee higher reliability and quality in software, and promotes
open standards that can result in rapid growth – the Internet itself through its essential open
sourced TCP/IP protocol being the most obvious example. Open source frees end users from a

16. single supplier controlled market and is very future-proof because a huge pool of independent
developers are working on successful projects, assuring the existence of necessary updates.
References
1. St. Laurent, Andrew M. (2008). Understanding Open Source and Free Software
Licensing. O'Reilly Media. p. 4. ISBN 9780596553951.
2. Verts, William T. (2008-01-13). "Open source software". World Book Online Reference
Center.
3. Rothwell, Richard (2008-08-05). "Creating wealth with free software". Free Software
Magazine. Retrieved 2008-09-08.
4. "Standish Newsroom — Open Source" (Press release). Boston. 2008-04-16. Retrieved
2008-09-08.
5. Perens, Bruce. Open Sources: Voices from the Open Source Revolution. O'Reilly Media.
1999.
6. The Open Source Definition by Bruce Perens. January 1999. ISBN 1-56592-582-3.
7. "The Open Source Definition"., The Open Source Definition according to the Open
Source Initiative
8. "How Many Open Source Licenses Do You Need? – Slashdot". News.slashdot.org. 2009-
02-16. Retrieved 2012-03-25.
9. Stallman, Richard (June 16, 2007). "Why "Open Source" misses the point of Free
Software". Philosophy of the GNU Project. Free Software Foundation. Retrieved July 23,
2007. "As the advocates of open source draw new users into our community, we free
software activists have to work even more to bring the issue of freedom to those new
users' attention. We have to say, 'It's free software and it gives you freedom!'—more and
louder than ever. Every time you say 'free software' rather than 'open source,' you help
our campaign."
10. Stallman, Richard (June 19, 2007). "Why "Free Software" is better than "Open Source"".
Philosophy of the GNU Project. Free Software Foundation. Retrieved July 23, 2007.
"Sooner or later these users will be invited to switch back to proprietary software for
some practical advantage. Countless companies seek to offer such temptation, and why
would users decline? Only if they have learned to value the freedom free software gives
them, for its own sake. It is up to us to spread this idea—and in order to do that; we have
to talk about freedom. A certain amount of the 'keep quiet' approach to business can be
useful for the community, but we must have plenty of freedom talk too."