https://www.w3.org/TR/dwbp/#ReuseVocabularies
http://fsfe.org/activities/os/def.el.html
http://5stardata.info
https://inkdroid.org/2010/06/04/the-5-stars-of-open-linked-data/
http://opendefinition.org/
https://en.wikipedia.org/wiki/Creative_Commons_license