1. G. R. Willey, A. L. Smith, G. Tourtellot, III, and I. Graham, Pap. Peabody Mus. Aichaeol. Ethnology. Harv. Univ. 13 (1), 20 (1975).
2. E. Huntington, Civilization and Climate (Yale Univ. Press, New Haven, 1915); Int. Cong. Amer. 19 (1917).
3. J. L. Page, Carnegie Inst. Wash. Publi., 431 (1933) and 437 (1938).
4. R. F. Hatt et al., Cransbrook Inst. Sci. 33 (1953) pp. 3809.
5. W. A. Sanchez and J. E. Kutzbach, Quarter. Res. 4 (1974).