Occasional papers of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1901)

Occasional papers of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1905)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1893)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1900)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1975)

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

Occasional papers on mollusks - Harvard University. Museum of Comparative Zoology. Department of Mollusks. (Dept. of Mollusks, 1947)

Occasional papers on mollusks - Harvard University. Museum of Comparative Zoology. Department of Mollusks. (Dept. of Mollusks, 1989)

Occasional papers on mollusks - Harvard University. Museum of Comparative Zoology. Department of Mollusks. (Dept. of Mollusks, 1992)

Occasional papers on mollusks - Harvard University. Museum of Comparative Zoology. Department of Mollusks. (Dept. of Mollusks, 1998)

Oceanus - Woods Hole Oceanographic Institution. (Woods Hole Oceanographic Institution, 1989)

Official catalogue of exhibitors. Universal exposition. St. Louis, U.S.A. 1904. : Division of exhibits. Department A. Education [to H. Agriculture; J. Horticulture to P. Physical Culture; R. Livestock.] (For the Committee on press and publicity by the official catalogue company inc, 1904)

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

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)

Officials charged with the enforcement of food laws in the United States and Canada - United States. Bureau of Chemistry. (Govt. print. off.], 1904)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1863)

The Ohio journal of science - Ohio Academy of Science. (Ohio Academy of Science, 1915)

Okens Lehrbuch der Naturgeschichte - Oken, Lorenz, 1779 -1851 (Bei Carl Heinrich Reclam, 1815)

On growth and form - Thompson, D'Arcy Wentworth, 1860 -1948 (University press, 1917)

On growth and form - Thompson, D'Arcy Wentworth, 1860 -1948 (University Press, 1945)

On horse-breaking - Moreton, Robert. (Longmans, Green, and Co, 1877)

On horse-breaking - Moreton, Robert. (Longmans, Green, 1877)

On orthogenesis : and the impotence of natural selection in species formation - Eimer, Theodor, 1843 -1898 (The Open Court Publishing Co, 1898)

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

On the Cambrian faunas of North America preliminary studies - Walcott, Charles D. (Charles Doolittle), 1850 -1927 (G.P.O, 1884)

On the classification and geographical distribution of Crustacea - Dana, James Dwight, 1813 -1895 (C. Sherman, 1853)

On the classification and geographical distribution of crustacea; from the report on crustacea of the United States exploring expedition, under Captain Charles Wilkes, U.S.N., during the years 1838-1842 - Dana, James Dwight, 1813 -1895 (Sherman, 1853)

On Turritopsis nutricula (McCrady) - Brooks, William Keith, 1848 -1908 (1907)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1900)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1901)

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)

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, 1955)

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, 1954)

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, 1956)

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, 1957)

Orchard and garden (J.T. Lovett, 1889)

Orchard and garden (J.T. Lovett, 1890)

Die organischen Regulationen, Vorbereitungen zu einer Theorie des Lebens - Driesch, Hans, 1867 -1941 (Engelmann, 1901)

The organism as a whole, from a physico-chemical viewpoint - Loeb, Jacques, 1859 -1924 (Putnam, 1916)

The organism as a whole : from a physicochemical viewpoint - Loeb, Jacques, 1859 -1924 (G. P. Putnam's sons, 1916)

The organism as a whole, from a physicochemical viewpoint - Loeb, Jacques, 1859 -1924 (Putnam's Sons, 1916)

The origin and evolution of life, on the theory of action, reaction and interaction of energy - Osborn, Henry Fairfield, 1857 -1935 (C. Scribner's Sons, 1917)

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)

The origin of the material universe; with a description of the manner of the formation of the earth, and events connected therewith, from its existence in a fluid state to the time of the mosaical narrative (Phillips, Sampson, 1850)

The Orthoptera of Indiana : an illustrated descriptive catalogue of the species known to occur in the state, with bibliography, synonymy and descriptions of new species - Blatchley, W. S. (Willis Stanley), 1859 -1940 ([Indiana Dept. of Geology and Natural Resources, 1903)

Orthoptera of northeastern America : with especial reference to the faunas of Indiana and Florida - Blatchley, W. S. (Willis Stanley), 1859 -1940 (Nature Pub. Co., 1920, 1920)

The Osprey (The Osprey Co, 1896)

Ostasiastische Dekapoden - Doflein, Franz, 1873 -1924 (Verlag der k. Akademie in Commission des G. Franz'schen Verlags (J. Roth), 1902)