http://www.natgeo.ro/istorie/civilizatii-stravechi/8352?start=2http://www.natgeo.ro/istorie/civilizatii-stravechi/9246-maya-vestigiile-mormintelor-scufundatehttp://www.natgeo.ro/istorie/civilizatii-stravechi/9227-orasul-regal-mayashttp://www.natgeo.ro/istorie/civilizatii-stravechi/8352-civilizatia-mayapoze: http://www.natgeo.ro/galerii-foto/category/8358-civilizatia-mayaalte calendare: http://www.webexhibits.org/calendars//calendar-ancient.htmlbabylonian, egiptean,asirian,, hititii, iran(persieni) vichingi,iulian, roman, ethiopian, persian,balinese, baha'i,http://www.onlineschooling.net/ancient-calendars