http://www.halldavidson.net/chartshort.html
http://www.pbssocal.org/education/teachers/copyright/
http://www.loc.gov/teachers/usingprimarysources/copyright.html
http://www.copyright.gov/
http://www.copyright.gov/circs/circ21.pdf
https://www.theedublogger.com/2012/02/09/the-educators-guideto-copyright-fair-use-and-creative-commons/
https://www.copyright.com/Services/copyrightoncampus/basics/fa
iruse_rules.html
http://www.halldavidson.net/chartshort.html
https://creativecommons.org/
http://www.educationworld.com/a_curr/curr280.shtml
https://www.teachingcopyright.org/
https://www.coursera.org/learn/copyright-for-education
http://www.pbssocal.org/education/teachers/copyright/