1. Dillehay, T.D. Scient. Am. 251(4), 100 (1984).
2. Bryan, A.L. & Beltro, M.C. in Early Man in America from a circum-Pacific Perspective (ed. Bryan, A.L.) 303 (Univ. Alberta, Edmonton, 1978).
3. Guidon, N. & Delibrias, G. Nature 321, 769 (1986).
4. Martin, P.S. & Klein, R.G. (eds) Quaternary Extinctions, A Prehistoric Revolution (University of Arizona, Tucson, 1984).
5. Bada, J.L. Am. Antiquity 50, 645 (1985).