Freidel, David A., Linda Schele, and Joy Parker. 1993. Maya Cosmos: Three Thousand Years on the Shaman's Path. New York: W. Morrow: 313, Fig. 7:19
Schele, Linda, and Peter Mathews. 1998. The Code of Kings: The Language of Seven Sacred Maya Temples and Tombs. New York: Scribner: 8: 90-91, Fig. 2.23