Heyden, Doris. “An Interpretation of the Cave underneath the Pyramid of the Sun in Teotihuacan, Mexico.” American Antiquity 40, no. 2 (1975): 131–47. https://doi.org/10.2307/279609.
Millon, Rene. “The Pyramid of the Sun at Teotihuacán: 1959 Investigations.” Transactions of the American Philosophical Society 55, no. 6 (1965): 1-93. : https://www.jstor.org/stable/1005892