Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1974)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1975)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1976)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1977)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1978)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1980)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1986)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1989)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1990)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1991)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1992)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1993)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1994)

Occasional papers of the Natural History Museum, the University of Kansas, Lawrence, Kansas - University of Kansas. Museum of Natural History. (The University, 1995)

Occasional papers of the Natural History Museum, the University of Kansas, Lawrence, Kansas - University of Kansas. Museum of Natural History. (The University, 1996)

Occasional papers of the San Diego Society of Natural History - San Diego Society of Natural History. (San Diego Society of Natural History, 1964)

Ohio Biological Survey notes - Ohio Biological Survey. (Ohio Biological Survey, 2011)

On Atopophrynus, a recently described frog wrongly assigned to the Dendrobatidae - Myers, Charles W. (American Museum of Natural History, 1986)

On the anatomy of vertebrates - Owen, Richard, 1804 -1892 (Longmans, Green, 1866)

On the anatomy of vertebrates ... - Owen, Richard, 1804 -1892 (Longmans, Green and Co, 1866)

On the reptiles and Batrachians of North America - Garman, Samuel, 1843 -1927 (Major, Johnston & Barrett, Yeoman, 1883)

On the structure and development of the skull in the Batrachia - Royal Society (Great Britain) (Royal Society, 1881)

On the structures and distribution of the genera of the arciferous Anura - Cope, E. D. (Edward Drinker), 1840 -1897 (s.n, 1866)

Opinions and declarations rendered by the International Commission on Zoological Nomenclature - International Commission on Zoological Nomenclature (Printed by order of the International Trust for Zoological Nomenclature, 1958)

The origin of the fittest : essays on evolution - Cope, E. D. (Edward Drinker), 1840 -1897 (Macmillan and Company, 1887)

Outlines of economic zoölogy - Reese, A. M. (Albert Moore), 1872 -1965 (P. Blakiston's Son & Co, 1919)

Paleocene amphibians from Cernay, France - Estes, Richard (American Museum of Natural History, 1967)

Pamietnik Fizyjograficzny (Druk K. Kowalewskiego, 1918)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1982)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1995)

Panamá : puente biológico : las Charlas Smithsonian del Mes, 1996-1999 - Heckadon Moreno, Stanley. (Instituto Smithsonian de Investigaciones Tropicales, 2001)

Papéis avulsos do Departamento de Zoologia - São Paulo Departamento de Zoologia (A Secretaria, 1941)

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Partnerships for sustainable forest ecosystem management : fifth Mexico/U.S. biennial symposium : October 17-20, 1994, Guadalajara, Jalisco, Mexico - Rocky Mountain Forest; Range Experiment Station (Fort Collins, Colo.) (U.S. Dept. of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station, 1995)

Perú: Cordillera Escalera-Loreto - Stotz, Douglas F. (Douglas Forrester), 1956 - (The Field Museum, Science and Education, 2014)

Peru : Ere-Campuya-Algodón - Field Museum of Natural History. (The Field Museum, Science and Education, 2013)

Peru : Maijuna - Alverson, William Surprison (Field Museum, Environment, Culture and Conservation, 2010)

Perú : Cerros de Kampankis - Stotz, Douglas F. (Douglas Forrester), 1956 - (The Field Museum, Environment, Culture, and Conservation, 2012)

Perú, Medio Putumayo-Algodón - Stotz, Douglas F. (Douglas Forrester), 1956 - (Field Museum of Natural History, 2016)

Perú : Nanay-Mazán-Arabela - Alverson, William Surprison (Field Museum, Environmental and Conservation Programs, 2007)

Perú : Tapiche-Blanco - Field Museum of Natural History. (The Field Museum, 2015)

Perú : Yaguas-Cotuhé - Field Museum of Natural History. (Field Museum, Environment, Culture, and Conservation, 2011)

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Philosophical transactions of the Royal Society of London - Royal Society (Great Britain) (Royal Society of London, 1881)