Sources

http://library.thinkquest.org/06aug/00418/mayanball.html

http://en.wikipedia.org/wiki/Maya_calendar

http://www.oneworldjourneys.com/jaguar/history.html

http://jameswatt.me/2012/03/07/mayan-calendar-and-the-gregorian-leap-year/

http://www.youtube.com/watch?v=wLsQYsE7Im8

http://www.religionfacts.com/mayan_religion/index.htm