Occasional paper - Entomological Society of British Columbia (The Society, 1994)

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

Occasional papers - Texas Tech University. Museum, (The Museum, 1979)

Occasional papers - Texas Tech University. Museum, (The Museum, 1985)

Occasional papers of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1921)

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, 1970)

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)

Oeuvres de Descartes - France. Ministère de l'Instruction publique (L. Cerf, 1897)

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 Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1860)

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

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1865)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1871)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1872)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1875)

Ohio beetles bulletin - Ohio Coleopterists Society (Ohio Coleopterist Society, 2012)

Om Sveriges hydrachnider - Neuman, Carl Julius, 1839 -1912 (Kongl. boktryckeriet, P.A. Norstedt & söner, 1880)

On animal and vegetable parasites of the human body a manual of their natural history, diagnosis, and treatment - Lankester, Edwin, 1814 -1874 (Printed for the Sydenham Society, 1857)

On animal and vegetable parasites of the human body, a manual of their natural history, diagnosis, and treatment - Küchenmeister, Friedrich, 1821 -1890 (Printed for the Sydenham Society, 1857)

On Brucharachne, the spider that wasn't (Arachnida, Acari, Dermanyssoidea) - Platnick, Norman I. (American Museum of Natural History, 1995)

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

On the habits and instincts of animals - Swainson, William, 1789 -1855 (Printed for Longman, Orme, Brown, Green, & Longmans, 1840)

On the history and natural arrangement of insects - Shuckard, William Edward, 1802 -1868 (Printed for Longman, Brown, Green & Longman's Paternoster Row, 1840)

On the history and natural arrangement of insects - Shuckard, William Edward, 1802 -1868 (Printed for Longman, Orme, Brown, Green, & Longmans [etc.], 1840)

On the medico-legal application of entomology - Johnston, Wyatt, 1863 -1902 (s.n, 1897)

On the natural history and classification of birds - Swainson, William, 1789 -1855 (John Taylor, 1836)

On the Natural History and classification of Birds : vol. I and II - Swainson, William, 1789 -1855 (pr. for Longman [etc.], 1836)

On the North American species of the genus Atax (Fabr.) Bruz - Wolcott, Robert Henry, 1868 -1934 (University of Nebraska, 1899)

On the origin and metamorphoses of insects - Lubbock, John, Sir, 1834 -1913 (Macmillan, 1874)

On the origin and metamorphoses of insects - Lubbock, John, Sir, 1834 -1913 (Macmillan and co, 1874)

On the power, wisdom and goodness of God, as manifested in the creation of animals, and in their history, habits and instincts - Kirby, William, 1759 -1850 (Carey, Lea & Blanchard, 1836)

On the young stages of some osseous fishes. I-III ... - Agassiz, Alexander, 1835 -1910 (1878)

On two orders of Arachnida : Opiliones, especially the suborder Cyphophthalmi, and Ricinulei, namely the family Cryptostemmatoidae - Royal Society (Great Britain) (University Press, 1904)

The onion (ICAR-Directorate of Knowledge Management in Agriculture, Indian Council of Agricultural Research, 2015)

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)

Opuscoli scientifici d'entomologia, di fisica e d'agricoltura - Termeyer, Ramón María, 1737 -1814 (Nella Stamperia del Giornale italico di Carlo Dova, contrada S. Rafaello, num. 998, 1807)

Opuscula zoologica - Zoologische Staatssammlung München. (Zoologische Staatssammlung, 1957)

Opuscula zoologica - Zoologische Staatssammlung München. (Zoologische Staatssammlung, 1965)

Opuscula zoologica - Zoologische Staatssammlung München. (Zoologische Staatssammlung, 1967)

Opuscula zoologica - Zoologische Staatssammlung München. (Zoologische Staatssammlung, 1969)

Opuscula zoologica - Zoologische Staatssammlung München. (Zoologische Staatssammlung, 1971)

Opuscula zoologica - Zoologische Staatssammlung München. (Zoologische Staatssammlung, 1975)

The orchard and fruit garden: their culture and produce - Watts, Elizabeth. (F. Warne & Co, 1867)

The Orchid review (Orchid Review ltd.], 1898)

The organization of Trilobites, deduced from their living affinities. With a systematic review of the species hitherto described - Bell, Thomas, 1792 -1880 (Printed for the Ray Society, 1846)

The origin of life and process of reproduction in plants and animals : with the anatomy and physiology of the human generative system, male and female, and the causes, prevention and cure of the special diseases to which it is liable : a plain, practical treatise, for popular use - Hollick, Frederick, 1818 -1900 (David McKay, 1902)

Ornamental gardening in Florida - Simpson, Charles Torrey, 1846 -1932 (The author, 1916)

Ornithological gazetteer of Argentina - Paynter, Raymond A. Jr. (Obtainable from Bird Dept., Museum of Comparative Zoology, Harvard University, 1995)

Ornithological gazetteer of Brazil - Traylor, Melvin A. (Melvin Alvah), 1915 -2008 (Obtainable from Bird Dept., Museum of Comparative Zoology, Harvard University, 1991)

Ornithological gazetteer of Peru - Traylor, Melvin A. (Melvin Alvah), 1915 -2008 (Bird Dept., Museum of Comparative Zoology, Harvard University, 1983)

Osservazioni naturali intorno alle cavallette nocive della Campagna Romana / [da Luigi Metaxa e Sebastiano Rolle] - Rolle, Sebastiano, (Vincenzo Poggioli, 1825)

Our common insects; first steps to entomology - Cox, Rosalinda Alicia (R. Hardwicke, 1869)

Our common insects. A popular account of the insects of our fields, forests, gardens and houses - Packard, A. S. (Alpheus Spring), 1839 -1905 (Naturalists' Agency, 1873)

Our common insects A popular account of the insects of our fields, forests, gardens, and houses - Packard, A. S. (Alpheus Spring), 1839 -1905 (Estes and Lauriat, 1873)

Our domestic animals in health and disease - Gamgee, John, 1831 -1894 (Maclachlan & Stewart, 1871)

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Our living world; an artistic edition of the Rev. J. G. Wood's Natural history of animate creation - Wood, J. G. (John George), 1827 -1889 (S. Hess, 1885)

Ouresiphoitēs Helveticus, sive, Itinera per Helvetiae Alpinas regiones facta annis MDCCII, MDCCIII, MDCCIV, MDCCV, MDCCVI, MDCCVII, MDCCIX, MDCCX, MDCCXI : plurimis tabulis aeneis illustrata - Scheuchzer, Johann Jakob, 1672 -1733 (Typis ac sumptibus Petri Vander Aa, 1723)

Outlines of entomology, published in connection with the author's annual reports upon injurious insects. Part first. Including the order of coleoptera - LeBaron, William. (State Journal Steam Print, 1874)

Outlines of general zoology - Baird, Spencer Fullerton, 1823 -1887 (Rudolph Garrigue, 1851)

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Pacific science - University of Hawaii. (University Press of Hawaii, 1961)

Pacific science - University of Hawaii. (University Press of Hawaii, 1965)

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Palaeontology - Palaeontological Association (Palaeontological Association, 1977)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1949)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1952)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1954)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1956)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1958)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1960)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1962)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1964)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1965)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1966)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1968)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1969)

The Pan-Pacific entomologist - Van Duzee, Edward P. (Edward Payson), 1861 -1940 (Pacific Coast Entomological Society, 1970)