Charles C. Thomas, Springfield, Illinois, 1935.
Darwin, Charles,
The Descent of Man (reprint of second edition, 1874), A. L. Burt Co., New York.
Da Vinci, Leonardo, A Treatise on Painting, George Bell & Sons, London, 1877.
Day, R. H.,
Human
John Wiley & Sons, Sydney, Australia, 1969.
Dean, Stanley R., editor.
Nelson-Hall, Chicago, 1975.
De Givry, Grillot,
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