30. http://schema.org/
Informazioni su rich snippet e dati strutturati:
https://support.google.com/webmasters/answer/99170?hl=it
http://www.microdatagenerator.com/
http://www.google.com/webmasters/tools/richsnippets
http://html5doctor.com/microdata/
http://diveintohtml5.info/extensibility.html