1. Bendersky, G. (1997). The Olmec heart effigy: Earliest image of the human heart. Perspectives in Biology and Medicine, 40, 348–361.
2. Bendersky, G. (2000). Tlatilco sculptures, diprosopus, and the emergence of medical illustrations. Perspectives in Biology and Medicine, 43(4), 477–501.
3. Bureau of American Ethnology Bulletin;P Drucker,1952
4. Bureau of American Ethnology Bulletin;P Drucker,1955
5. England, M. (1996). Life before birth (2nd ed.). London: Mosby-Wolfe.