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Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2010)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2013)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1971)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1972)

Occasional papers of the Museum of Natural History, the University of Kansas - University of Kansas. Museum of Natural History. (The University, 1973)

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, 1984)

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 Zoology, University of Michigan - University of Michigan. Museum of Zoology. (University of Michigan, 1921)

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 - Tulane University. Museum of Natural History. (The Museum, 1982)

Odontographie. Vergleichende Darstellung des Zahnsystemes der lebenden und fossilen Wirbelthiere - Giebel, C. (Christoph), 1820 -1881 (A. Abel, 1855)

The official guide to the Norwich Castle Museum - Southwell, Thomas, 1831 -1909 (Jarrold & Sons, 1895)

Official lists and indexes of names and works in zoology Supplement 1986-2000 - International Commission on Zoological Nomenclature (International Trust for Zoological Nomenclature, c/o Natural History Museum, 2001)

Öfversigt af Finska vetenskaps-societetens förhandlingar - Suomen Tiedeseura (s.n.], 1838)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1845)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1876)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1878)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1879)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1883)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1884)

Ohrknorpel und äusseres ohr der Säugetiere; eine vergleichend-anatomische Untersuchung - Boas, J. E. V. (Johan Erik Vesti), 1855 -1935 ([Nielsen & Lydiche (A. Simmelkiær)], 1912)

Oikos= boletín del Centro de Ecología [UNAM] (Instituto de Ecología, UNAM, 2012)

Oikos= boletín del Centro de Ecología [UNAM] (Instituto de Ecología, UNAM, 2015)

Oil and gas leasing on lands administered by Dixie National Forest : draft environmental impact statement - United States. Bureau of Land Management. Desert Planning Staff - (U.S. Department of Agriculture, Forest Service, Intermountain Region, 1995)

Oil spill sensitivity of the western Indian Ocean islands: coastal data from the Comoros Islands, Madagascar, Mauritius, Reunion and the Seychelles - Green, Edmund P. (Edmund Peter) 1965 - (WCMC, 1998)

L'Oiseau et la Revue francaise d'ornithologie - Société ornithologique de France. (Société ornithologique de France, 1979)

The Oligocene Hsanda Gol Formation, Mongolia : a revised faunal list - Mellett, James Silvan, 1936 - (American Museum of Natural History, 1968)

Om rätta tydningen af sido-utskotten på rygg- och ländkotorna hos menniskan och däggdjuren - Retzius, A. (Anders), 1796 -1860 (Norstedt, 1850)

Om slägtet Sorex, med några nya arters beskrifning - Sundevall, Carl J., 1801 -1875 (Kungliga Vetenskapsakademien, 1842)

On mammalian descent. Being nine lectures delivered in the theatre of the Royal College of Surgeons during February, 1884 - Parker, William Kitchen William Kitchen Parker 1823 -1890 (Griffin, 1885)

On mammalian descent the Hunterian Lectures for 1884 : being nine lectures delivered in the theatre of the Royal College of Surgeons during February, 1884 - Parker, William Kitchen William Kitchen Parker 1823 -1890 (C. Griffin, 1885)

On mammalian descent; the Hunterian Lectures for 1884; being nine lectures delivered in the theatre of the Royal College of Surgeons during February, 1884 - Parker, William Kitchen William Kitchen Parker 1823 -1890 (Charles Griffin, 1885)

On "retrogression" in the evolution of the Phocinae and phylogenetic affinities of the monk seals - Wyss, André R. (American Museum of Natural History, 1988)

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 structure and development of the skull in the mammalia - Parker, William Kitchen William Kitchen Parker 1823 -1890 (Royal Society of London, 1874)

On the taxonomic identity of Pteronotus davyi incae Smith, 1972 (Chiroptera: Mormoopidae) - Pacheco, Víctor (American Museum of Natural History, 2021)

On the taxonomic identity of Sturnira nana Gardner and O'Neil, 1971 (Chiroptera: Phyllostomidae), from Ecuador : with the description of a new species of Sturnira - Velazco, Paúl M. (American Museum of Natural History, 2023)

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 orders of mammals - Gregory, William K. (William King), 1876 -1970 (The Trustees, 1910)

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

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

The origin of the fittest; essays on evolution - Cope, E. D. (Edward Drinker), 1840 -1897 (D. Appleton, 1887)

Ornithologisches Jahrbuch (V. Tschusi, 1915)

Osteology of Andescynodon (Cynodontia, Traversodontidae) from the Middle Triassic of Argentina - Powell, Jaime Eduardo. (American Museum of Natural History, 2009)

Our country's animals and how to know them. A guide to the mammals, reptiles and amphibians of Great Britain - Gordon, W. J. (Simpkin, Marshall, Hamilton, Kent, 1904)

Our wildlife and its wise use - Donat, Winfield. (Wildlife Resources Commission, 1948)