Snedecor, G. W.
1956. Statistical methods. Iowa St. College Press, Ames, Iowa, 5th ed., xiii + 534 pp.
Stebbins, R. C.
1954. Amphibians and reptiles of western North America. McGraw-Hill Book Co., New York, vii + 528 pp., 104 pls., 52 figs.
Stein, H. A.
1954. Additional records of amphibians and reptiles in southern Illinois. Amer. Midl. Nat., 51(1):311-12.
Stejneger, L.
1907. Herpetology of Japan and adjacent territory. Bull. U. S. Nat. Mus., 58:xx + 577 pp., 409 figs., 35 pls.
1944. Notes on the American soft-shell turtles, with special reference to Amyda agassizii. Bull. Mus. Comp. Zool., 94(1):1-75 pp., 30 pls., 10 tables, May.
Stejneger, L., and Barbour, T.