Les oiseaux du Canada - Dionne, C.-E. (Charles-Eusèbe), 1846 -1925 (P. G. Delisle, 1883)

Les oiseaux du Canada - Dionne, C.-E. (Charles-Eusèbe), 1846 -1925 (s.n.], 1883)

Les oiseaux - Perrier, Edmond, 1844 -1921 (J.B. Bailli, 1904)

Oiseaux - Fédération des sociétés françaises de sciences naturelles. Office central de faunistique. (P. Lechevalier, 1921)

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

Okens Lehrbuch der Naturgeschichte - Oken, Lorenz, 1779 -1851 (Bei Carl Heinrich Reclam, 1816)

Oländska och Gothländska resa : på riksens hògloflige ständers befallning forrättad åhr 1741. Med anmärkningar uti oeconomien, natural-historien, antiquiteter &c. med ätskillige figurer - Linné, Carl von, 1707 -1778 (Mos Gottfried Kiesewetter, 1745)

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)

On a collection of birds from North-Eastern Abyssinia and the Bogos Country - Jesse, William. (Zoological Society of London, 1870)

On a collection of birds made by Dr. Ernst Mayr in northern Dutch New Guinea - Mayr, Ernst, 1904 -2005 (Zoological Museum, 1930)

On safari : big game hunting in British East Africa with studies in bird-life - Chapman, Abel, 1851 -1929 (Edward Arnold, 1908)

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 batrachia and reptilia of Costa Rica : With notes on the herpetology and ichthyology of Nicaragua and Peru - Cope, E. D. (Edward Drinker), 1840 -1897 (s.n, 1875)

On the birds' highway - Fuertes, Louis Agassiz, 1874 -1927 (Small, Maynard & Company, 1899)

On the birds of the islands of Aruba, Curaçao, and Bonaire - Hartert, Ernst, 1859 -1933 (s.n, 1893)

On the egg-tooth of snakes and lizards, with a plate on the armature of the lower bill of the hatching Tring Pusilla...Wilson - Weinland, D. F. (David Friedrich), 1829 -1915 (William Ives and George W. Pease, Printers, 1857)

On the geology and natural history of the upper Missouri :Being the substance of a report made to Lieut. G.K. Warren, T.E. U.S.A - Hayden, F. V. (Ferdinand Vandeveer), 1829 -1887 (Printed by C. Sherman & son, 1862)

On the intestinal tract of birds; with remarks on the valuation and nomenclature of zoological characters - Mitchell, P. Chalmers Sir, (Peter Chalmers), 1864 -1945 (1901)

On the mental qualities of birds, as compared with their cerebral development - MacGillivray, John, 1821 -1867 (Adam and Charles Black, 1824)

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 varieties of the shells belonging to the genus Nassa, Lam - Marrat, F. (1880)

Onze vogels in huis en tuin - Keulemans, J. G. (John Gerrard), 1842 -1912 (P.W.M. Trap, 1869)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1887)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1891)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1893)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1894)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1898)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1913)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1914)

Ootheca Wolleyana: an illustrated catalogue of the collection of birds' eggs - Newton, Alfred, 1829 -1907 (sold by R. H. Porter, 1905)

Ootheca Wolleyana: an illustrated catalogue of the collection of birds' eggs - Newton, Alfred, 1829 -1907 (sold by R. H. Porter, 1907)

Opera ornithologica - Bonaparte, Charles-Lucien, 1803 -1857 (1857)

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, 1947)

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, 1956)

Opuscula ornithologica : notis et addendis, mss - Coues, Elliott, 1842 -1899 (1861)

The Oregon naturalist (Naturalist Pub. Co, 1896)

L'Organisation du Règne animal. Oiseaux - Blanchard, Emile, 1819 -1900 (Chez l'Auteur)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1885)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1886)