Irwin-Williams, Cynthia (1967a) “Associations of Early Man with Horse, Camel, and Mastodon at Hueyatlaco, Valsequillo (Puebla, Mexico)” in Pleistocene Extinctions - the Search for a Cause. Edited by P. S. Martin and H. E. Wright. New Haven: Yale University Press, pp. 337-350.
-- (1967b) “Comments on Allegations by J. L. Lorenzo Concerning Archaeological Research at Valsequillo, Puebla” in Paleo-Indian Institute, Eastern New Mexico University Miscellaneous Publications, Number 1, Portales.
-- (1969) “Comments on the Associations of Archaeological Materials and Extinct Fauna in the Valsequillo Region, Puebla, Mexico” in American Antiquity 34: 82-83.10.2307/278319
-- (1978) “Summary of Archaeological Evidence from the Valsequillo Region, Puebla, Mexico” in Cultural Continuity in Mesoamerica. Edited by David L. Browman. The Hague: Mouton Publishers.
Malde, Harold E. and Virginia Steen-McIntyre (1981) “Reply to Comments by C. Irwin-Williams: Archaeological Site, Valsequillo, Mexico” in Quaternary Research 16:418-425.10.1016/0033-5894(81)90020-X
Steen-McIntyre, Virginia (1980) “Approximate Dating of Tephra.” Presented at NATO Advanced Studies Institute on Tephrochronology, Iceland, June 1980.10.1007/978-94-009-8537-7_3
Steen-McIntyre, Virginia, Roald Fryxell, and Harold E. Malde (1981) “Geologic Evidence for Age of Deposits at Hueyatlaco Archeological Site, Valsequillo, Mexico” in Quaternary Research 16:1-17.10.1016/0033-5894(81)90124-1
Szabo, Barney J., Harold E. Malde, and Cynthia Irwin-Williams (1969) “Dilemma Posed by Uranium-Series Dates on Archaeologically Significant Bones from Valsequillo, Puebla, Mexico” in Earth and Planetary Science Letters 6:237-244.10.1016/0012-821X(69)90163-0