http://www.britannica.com/EBchecked/topic/370875/Mayan-hieroglyphic-writing
http://www.ancientscripts.com/maya.html
http://www.astronomy-for-kids-online.com/ancient-mayan-astronomy.html
http://worsleyschool.net/socialarts/mayan/art.html
http://www.webexhibits.org/calendars/calendar-mayan.html
