Occasional papers - Texas Tech University. Museum, (The Museum, 1991)

Occasional papers - Texas Tech University. Museum, (The Museum, 2002)

Occasional papers - Texas Tech University. Museum, (The Museum, 2003)

Occasional papers - Texas Tech University. Museum, (The Museum, 2018)

Occasional papers of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1904)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2009)

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, 1988)

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

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

Odontography : or a treatise on the comparative anatomy of the teeth, their physiological relations, mode of development and microscopic structure, in the vertebrate animals - Owen, Richard, 1804 -1892 (Hippolyte Bailliere, 1840)

Odontography; or, A treatise on the comparative anatomy of the teeth; their physiological relations, mode of development, and microscopic structure, in the vertebrate animals - Owen, Richard, 1804 -1892 (H. Baillière, 1840)

Odontornithes : a monograph on the extinct toothed birds of North America with thirty-four plates and forty woodcuts - Marsh, Othniel Charles, 1831 -1899 (G.P.O, 1880)

Odontornithes: a monograph on the extinct toothed birds of North America; with thirty-four plates and forty woodcuts - Marsh, Othniel Charles, 1831 -1899 (Govt. print. off, 1880)

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)

Official lists and indexes of names and works in zoology - International Commission on Zoological Nomenclature (ICZN, 1987)

Öfversigt af Finska vetenskaps-societetens förhandlingar - Suomen Tiedeseura (s.n.], 1890)

Öfversigt af Finska vetenskaps-societetens förhandlingar - Suomen Tiedeseura (s.n.], 1918)

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, 1889)

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

Old bones : or, Notes for young naturalists - Brooks, Vincent, 1815? -1885 (Robert Hardwicke, 1861)

Old bones : or, Notes for young naturalists, on vertbebrate animals, their fossil predecessors and allies - Symonds, W. S. 1818 -1887 (Robert Hardwicke, 1864)

Oligocene marsupials of the Geilston Bay local fauna, Tasmania - Tedford, Richard H. (American Museum of Natural History, 1998)

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 a fossil Saurian of the new red sandstone formation of Pennsylvania, with some account of that formation : also: On some new fossil molluscs, in the carboniferous slates of the anthracite seams of the Wilkesbarre coal formation - Lea, Isaac, 1792 -1886 (Merrihew & Thompson, printers, 1852)

On a notostylopid from the Paleocene of Itaborai, Brazil - Couto, Carlos de Paula. (American Museum of Natural History, 1954)

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 some Mammalia of the Lowest Eocene beds of New Mexico - American Philosophical Society. ([publisher not identified], 1881)

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 classification and geographical distribution of the Mammalia, being a lecture on Sir Robert Reade's foundation, delivered before the University of Cambridge ... May 10, 1859. To which is added an appendix "On the gorilla," and "On the extinction and transmutation of species." - Owen, Richard, 1804 -1892 (J. W. Parker and son, 1859)