The following literature references are from Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo (©2005 by the Regents of the University of California), used with permission of University of California Press. The book is available from UC Press.

U.S. Congress, Office of Technology Assessment, Harmful Non-Indigenous Species in the United States. 1993. U.S. Government Printing Office, OTA-F-565, Washington, D.C.
U.S. Department of the Interior. 1991. Endangered and threatened wildlife and plants; animal notice of review. Federal Register, 50 CFR Part 17, 56:58804–58836.
U.S. Environmental Protection Agency. 1975. Methods for acute toxicity tests with fish, macroinvertebrates, and amphibians. Committee on Methods of Acute Toxicity Tests with Aquatic Organisms, National Environmental Research Center, EPA-660/3-75-009, Corvalis, Oregon.
U.S. Environmental Protection Agency. 1999. Draft map of Level III ecoregions of the continental United States. National Health and Environmental Effects Research Laboratory, Corvallis, Oregon.
U.S. Environmental Protection Agency. 2000a. Level III ecoregions of the continental United States (revision of Omernik, 1987), Map M-1. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Corvallis, Oregon.
U.S. Environmental Protection Agency. 2000b. Draft level III and IV ecoregions of the southeastern states. National Health and Environmental Effects Research Laboratory, Corvallis, Oregon.
U.S. Fish and Wildlife Service. 1976. Determination that the Red Hills salamander is a threatened species. Federal Register 41:53032–53034.
U.S. Fish and Wildlife Service. 1977. Endangered and threatened wildlife and plants; proposed determination of critical habitat for the Houston toad. Federal Register 42:27009–27011.
U.S. Fish and Wildlife Service. 1982. Desert slender salamander recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon.
U.S. Fish and Wildlife Service. 1989a. Determination of threatened status for the Cheat Mountain salamander and endangered status for the Shenandoah salamander. Federal Register 54:34464–34468.
U.S. Fish and Wildlife Service. 1989b. Endangered and threatened wildlife and plants: proposal to determine threatened status for the Cheat Mountain salamander and endangered status for the Shenandoah salamander. Federal Register, 50 CFR Part 17, Volume 53(188):37814–37818.
U.S. Fish and Wildlife Service. 1989c. Endangered and threatened wildlife and plants; animal notice of review. Federal Register 54:554–558.
U.S. Fish and Wildlife Service. 1990. Flattened musk turtle (Sternotherus depressus) recovery plan. USFWS, Jackson, Mississippi.
U.S. Fish and Wildlife Service. 1991. Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species, proposed rule. Federal Register 56:58804–58836.
U.S. Fish and Wildlife Service. 1993. Endangered and threatened wildlife and plants; finding on petition to list the spotted frog. Federal Register 58:38553.
U.S. Fish and Wildlife Service. 1994a. Endangered and threatened wildlife and plants; determination of endangered status for the arroyo southwestern toad. Federal Register 59:64859–64866.
U.S. Fish and Wildlife Service. 1994b. Endangered and threatened wildlife and plants; 12-month petition finding for the California tiger salamander. Federal Register 59:18353–18354.
U.S. Fish and Wildlife Service. 1994c. Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species; proposed rule. Federal Register 59(219):58982–59028.
U.S. Fish and Wildlife Service. 1994d. Shenandoah salamander (Plethodon shenandoah) recovery plan. U.S. Fish and Wildlife Service, Hadley, Massachusetts.
U.S. Fish and Wildlife Service. 1995a. Endangered and threatened wildlife and plants; 12-month finding for a petition to list the Southern Rocky Mountain population of the boreal toad as endangered. Federal Register 60:15281–15283.
U.S. Fish and Wildlife Service. 1995b. San Marcos and Comal Springs and associated aquatic ecosystems (revised) recovery plan. U.S.Fish and Wildlife Service Region 2, Albuquerque, New Mexico.
U.S. Fish and Wildlife Service. 1995c. Administrative 12-month finding on a not warranted petition to list the Amargosa toad under the Endangered Species Act. Memorandum to Director, Fish and Wildlife Service from Acting Regional Director, Region 1, dated 26 October, 1995.
U.S. Fish and Wildlife Service. 1996a. Endangered and threatened wildlife and plants; review of plant and animal taxa that are candidates for listing as endangered or threatened species. Federal Register 61(40):7596–7613.
U.S. Fish and Wildlife Service. 1996b. San Marcos and Comal Springs and associated aquatic ecosystems (revised) recovery plan. United States Fish and Wildlife Service Region 2 Office, Albuquerque, New Mexico.
U.S. Fish and Wildlife Service. 1996c. Endangered and threatened wildlife and plants: determination of threatened status for the California red-legged frog. Federal Register 61(101):25813-25833.
U.S. Fish and Wildlife Service. 1997a. Endangered and threatened species; review of plant and animal taxa; proposed rule. [Federal Register: September 19, 1997 (Volume 62, Number 182)] 50 CFR Part 17, Department of the Interior, Washington, D.C.
U.S. Fish and Wildlife Service. 1997b. Endangered and threatened wildlife and plants; notice of reclassification of ten candidate species. Federal Register 62:49191–49193.
U.S. Fish and Wildlife Service. 1997c. Endangered and threatened wildlife and plants; proposed rule to list the flatwoods salamander as threatened. Federal Register 62(241):65787–65794.
U.S. Fish and Wildlife Service. 1998a. Final environmental assessment/habitat conservation plan for issuance of a section 10(a)(1)(B) permit for incidental take of the Barton Springs salamander (Eurycea sosorum) for the operation and maintenance of Barton Springs Pool and adjacent springs, Austin, Texas.
U.S. Fish and Wildlife Service. 1998b. Headwaters Forest Project Final Environmental Impact Statement/ Environmental Impact Review and Pacific Lumber Company Habitat Conservation Plan. U.S. Fish and Wildlife Service, Arcata, California.
U.S. Fish and Wildlife Service. 1999a. Arroyo southwestern toad (Bufo microscaphus californicus) recovery plan. U.S. Department of the Interior, Fish and Wildlife Service, Portland, Oregon.
U.S. Fish and Wildlife Service. 1999b. Agency Draft. California red-legged frog (Rana aurora draytonii) Recovery Plan, Portland, Oregon.
U.S. Fish and Wildlife Service. 1999c. Santa Cruz long-toed salamander (Ambystoma macrodactylum croceum) draft revised recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon.
U.S. Fish and Wildlife Service. 2000a. Review of endangered and threatened wildlife and plants; proposal to list the Chiricahua leopard frog as threatened with a special rule. Federal Register 65:37343–37357.
U.S. Fish and Wildlife Service. 2000b. Endangered and threatened wildlife and plants; emergency rule to list the Santa Barbara County distinct population of the California tiger salamander as endangered. Federal Register 65:3095–3109.
U.S. Fish and Wildlife Service. 2001a. Tarahumara frog conservation program. http://arizonaes.fws.gov/T-frog3.htm.
U.S. Fish and Wildlife Service. 2001b. Changes in list of species in appendices to the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Federal Register 66(97):27601–27615.
U.S. Fish and Wildlife Service. 2002a. Endangered and threatened wildlife and plants; listing of the Chiricahua leopard frog (Rana chiricahuensis). Federal Register 67(114):40790–40810.
U.S. Fish and Wildlife Service. 2002b. Endangered and threatened wildlife and plants; determination of endangered status for the Southern California distinct vertebrate segment of the mountain yellow-legged frog (Rana muscosa). Federal Register 67(127):44382–44392.
U.S. Fish and Wildlife Service. 2002c. Recovery plan for the California red-legged frog (Rana aurora draytonii). U.S. Fish and Wildlife Service, Portland, Oregon.
U.S. Fish and Wildlife Service. 2002d. Status review for the Columbia spotted frog (Rana luteiventris) on the Wasatch Front, Utah. U.S. Department of the Interior, U.S. Fish and Wildlife Service, Region 6, Denver, Colorado.
U.S. Forest Service. 1988. Endangered Species Act of 1973 as Amended Through the 100th Congress. U.S. Department of the Interior, Washington, D.C.
U.S. General Accounting Office. 1991. Rangeland management: BLM’s hot desert grazing program merits reconsideration. Washington, D.C.
U.S. Senate and House of Representatives. 1973. Endangered Species Act of 1973. Public Law 93–205.
Ubelaker, J.E., D.W. Duszynski and D.L. Beaver. 1967. Occurrence of the trematode, Glypthelmins pennsylvaniensis Cheng, 1961, in chorus frogs, Pseudacris triseriata, in Colorado. Bulletin of the Wildlife Disease Association 3:177.
Uchida, A., H. Itagaki and H. Inoue. 1980. Studies on the amphibian helminths in Japan. VII. Rhacophotrema itagakii n. g. et n. sp, and Opisthioglyphe japonicus n. sp. (Digenea: Omphalometridae) from frogs. Japanese Journal of Parasitology 29:109–113.
Uhlenhuth, E. 1919. Observations on the distribution of the blind Texan cave salamander, Typhlomolge rathbuni. Copeia 69:26–27.
Uhlenhuth, E. 1921. Observations on the distribution and habitats of the blind Texan cave salamander, Typhlomolge rathbuni. Biological Bulletin 15:73–104.
Uhler, F.M., C. Cottam and T.E. Clarke. 1939. Food of snakes of the George Washington National Forest, Virginia. Pp. 605–622. In Transactions of the Fourth North American Wildlife Conference, Washington, D.C.
Ulmer, M.J. 1970. Studies on the helminth fauna of Iowa. I. Trematodes of amphibians. American Midland Naturalist 83:38–64.
Ulmer, M.J. and H.A. James. 1976. Studies on the helminth fauna of Iowa. II. Cestodes of amphibians. Proceedings of the Helminthological Society of Washington 43:191–200.
Ultsch, G.R. 1973. Observations on the life history of Siren lacertina. Herpetologica 29:304–305.
Ultsch, G.R. 1976. Eco-physiological studies of some metabolic and respiratory adaptations of sirenid salamanders. Pp. 287–311. In Hughes, G.M. (Ed.), Respiration of Amphibious Vertebrates. Academic Press, London.
Ultsch, G.R. and S.J. Arceneaux. 1988. Gill loss in larval Amphiuma tridactylum. Journal of Herpetology 22:347–348.
Ultsch, G.R., D.F. Bradford and J. Freda. 1999. Physiology: coping with the environment. Pp. 189–214. In McDiarmid, R.W. and R. Altig (Eds.), Tadpoles: The Biology of Anuran Larvae. University of Chicago Press, Chicago, Illinois.
Ultsch, G.R., T.E. Graham and C.E. Crocker. 2000. An aggregation of overwintering leopard frogs, Rana pipiens, and common map turtles, Graptemys geographica, in northern Vermont. Canadian Field-Naturalist 114:314–315.
Umber, R.W. and L.D. Harris. 1974. Effects of intensive forestry on succession and wildlife in Florida sandhills. Proceedings of the Annual Conference of Southeastern Association of Game and Fish Commissioners 28:686–693.
Underhill, D.K. 1966. An incidence of spontaneous caudal scoliosis in tadpoles of Rana pipiens Schreber. Copeia 1966:582–583.
Underhill, D.K. 1968a. Heritability of dorsal spot number and snout-vent length in Rana pipiens. Journal of Heredity 59:235–240.
Underhill, D.K. 1968b. Albino eggs and larvae of Ambystoma texanum in central Illinois. Herpetologica 24:266.
Underhill, J.C. 1958. Notes on the toads of eastern South Dakota. Copeia 1958:149–151.
Underhill, J.C. 1961. Intraspecific variation in the Dakota toad, Bufo hemiophrys, from northeastern South Dakota. Herpetologica 17:220–227.
Upchurch, D.J. 1971. Geographic distribution: Ambystoma maculatum. Herpetological Review 3:89.
Upton, S.J. and C.T. McAllister. 1988. The Coccidia (Apicomplexa: Eimeriidae) of Anura, with descriptions of four new species. Canadian Journal of Zoology 66:1822–1830.
Upton, S.J., C.T. McAllister and S.E. Trauth. 1993. The Coccidia (Apicomplexa: Eimeriidae) of Caudata (Amphibia), with descriptions of two new species from North America. Canadian Journal of Zoology 71:2410–2418.
URS Company. 1977. Las Vegas Wash interim report Number 2, Water Quality Series: Clark County 208 Water Quality Management Plan, Clark County, Nevada. U.R.S. Company, Las Vegas, Nevada.
Usher, M.B. (Ed.). 1986. Wildlife Conservation Evaluation. Chapman and Hall, London, England.
Utah Division of Wildlife Resources. 1991. Distribution and status of the western spotted frog in central Utah. Prepared for the U.S. Fish and Wildlife Service, Salt Lake City, Utah.
Uzendoski, U.V. and P.A. Verrell. 1993. Sexual incompatibility and mate-recognition systems: a study of two species of sympatric salamanders (Plethodontidae). Animal Behaviour 46:267–278.
Uzzell, T. 1963. Natural triploidy in salamanders related to Ambystoma jeffersonianum. Science 139:113–115.
Uzzell, T. 1967a. Ambystoma platineum. Pp. 49.1–49.2. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, St. Louis, Missouri.
Uzzell, T. 1967b. Ambystoma tremblayi. Pp. 50.1–50.2. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, St. Louis, Missouri.
Uzzell, T. 1969. Notes on spermatophore production by salamanders of the Ambystoma jeffersonianum complex. Copeia 1969:602–612.
Uzzell, T.M. 1952. Additional notes on the range of Rana grylio Stejneger in South Carolina. Copeia 1952:118.
Uzzell, T.M. 1963. Natural triploidy in salamanders related to Ambystoma jeffersonianum. Science 139:113–115.
Uzzell, T.M. 1963. Natural triploidy in salamanders related to Ambystoma jeffersonianum. Science 139:113–115.
Uzzell, T.M. 1964. Relations of the diploid and triploid species of the Ambystoma jeffersonianum complex (Amphibia: Caudata). Copeia 1964:257–300.
Uzzell, T.M. 1967a. Ambystoma jeffersonianum. Pp. 47.1–47.2. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, St. Louis, Missouri.
Uzzell, T.M. 1967b. Ambystoma laterale. Pp. 48.1–48.2. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, St. Louis, Missouri.
Uzzell, T.M. 1969. Notes on the spermatophore production by salamanders of the Ambystoma jeffersonianum complex. Copeia 1969:602–612.
Uzzell, T.M. 1969. Unisexual species of salamanders. Discovery 4:99–108.
Uzzell, T.M. and S.M. Goldblatt. 1967. Serum proteins of salamanders of the Ambystoma jeffersoniamum complex and the origin of the triploid species of this group. Evolution 21:345–354.
Uzzell, T.M., Jr. 1963. Natural triploidy in salamanders related to Ambystoma jeffersonianum. Science 139:113–115.
Uzzell, T.M., Jr. 1964. Relations of the diploid and triploid species of the Ambystoma jeffersonianum complex (Amphibia, Caudata). Copeia 1964:257–300.