Listed below are several references that are useful for identifying amphibians. Two references were utilized extensively in the preparation of these WebPages, Amphibians and Reptiles of the Pacific Northwest by R.A. Nussbaum, E.D. Brodie Jr., and R.M. Storm, and Amphibians of Washington and Oregon by W.P. Leonard, L.C. Jones, K.R. McAllister and R.M. Storm. These texts provide a much deeper coverage than what is synthesized here and it is suggested that you refer to them in addition to your exploration of these WebPages.
Altig, R.G. 1970. A key to the tadpoles of continental United States and Canada. Herpetologica 26(2): 180-207.
Baxter, G.T. and M.D. Stone. 1980. Amphibians and Reptiles of Wyoming. Wyoming Game and Fish Department Bull. 16, i-vi + 137 pp.
Behler, J.L. and F.W. King. 1979. The Audubon Society Field Guide to Reptiles and Amphibians. New York: Alfred A. Knopf. 719 pp.
Duellman, W.E. and L. Trueb. 1986. Biology of Amphibians. McGraw-Hill, Inc. 670pp.
Fichter E. and A.D. Linder. 1964. The Amphibians of Idaho. Idaho State University, Pocatello, Spec. Publ., 34 pp.
Goin C.J. and O.B. Goin. 1971. 2nd ed. Introduction to Herpetology. W.H. Freeman and Co., San Francisco, California. 353 pp.
Koch, E.D. and C.R. Peterson. 1995. Amphibians and Reptiles of Yellowstone and Grand Teton National Parks. University of Utah Press, Salt Lake City, Utah. 188 pp.
Leonard, W.P., H.A. Brown, L.L.C. Jones, K.R. McAllister, and R.M. Storm. 1993. Amphibians of Washington and Oregon. Seattle Audubon Society. 168 pp.
Linder A.D. and E. Fichter. 1977. The Amphibians and Reptiles of Idaho. Idaho State University Press, Pocatello, Idaho. 78 pp.
Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. The University Press of Idaho, Moscow, Idaho. 332pp.
Pough F.H., R.M. Andrews, J.E. Cadle, M.L. Crump, A.H. Savitzky and K.D. Wells. 1998. Herpetology. Prentice Hall, Upper Saddle River, New Jersey. 577pp.
Stebbins, R.C. 1985. A Field Guide to Western Reptiles and Amphibians. Houghton Mifflin Co., Boston. 279 pp.