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)

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

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 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 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 natural history of the Gulf of St. Lawrence and the distribution of the Mollusca of Eastern Canada - Bell, Robert, 1841 -1917 (s.n.], 1859)

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 structures and distribution of the genera of the arciferous Anura - Cope, E. D. (Edward Drinker), 1840 -1897 (s.n, 1866)

Onomasticon zoicon, plerorumque animalium differentias & nomina propria pluribus linguis exponens : cui accedunt Mantissa anatomica, et quaedam De variis fossilium generibus - Charleton, Walter, 1619 -1707 (Apud Jacobum Allestry ..., 1668)

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

The oölogist (J.M. Wade, 1876)

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, 1916)

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)

Oppian, Colluthus, Tryphiodorus, with an English translation by A.W. Mair - Colluthus, of Lycopolis. (W. Heinemann, 1928)

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

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

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

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1887)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1888)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1889)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1891)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1898)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1901)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1903)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1905)

Ornis Caucasica. Die Vogelwelt des Kaukasus : systematisch und biologisch-geographisch beschrieben - Radde, Gustav, 1831 -1903 (Verlag von Theodor Fischer, 1884)

Ornithologia methodice digesta, atque iconibus aeneis ad vivum illuminatis ornata - Lorenzi, Lorenzo. (In Aedibus Mouchianis, 1767)

Ornithologia methodice digesta, atque iconibus aeneis ad vivum illuminatis ornata - Lorenzi, Lorenzo. (In Aedibus Mouchianis, 1769)

Ornithologia methodice digesta, atque iconibus aeneis ad vivum illuminatis ornata - Lorenzi, Lorenzo. (In Aedibus Mouchianis, 1771)

Ornithologia methodice digesta, atque iconibus aeneis ad vivum illuminatis ornata - Lorenzi, Lorenzo. (In Aedibus Mouchianis, 1776)

Ornithologia, or, The birds: a poem, in two parts : with an introduction to their natural history; and copious notes - Jennings, James. (Sherwood, Gilbert, and Piper, 1829)

Ornithologia, sive, Synopsis methodica sistens avium divisionem in ordines, sectiones, genera, species, ipsarumque varietates : cum brevi & accurata cujusque speciei descriptione, citationibus auctorum de iis tractantium, nominibus eis ab ipsis impositis, nominibusque vulgaribus - Brisson, Mathurin-Jacques, 1723 -1806 (Apud Theodorum Haak, 1763)

Ornithologia Svecica - Nilsson, Sven, 1787 -1883 (Apud J.H. Schubothium, 1817)

Ornithologia Svecica - Nilsson, Sven, 1787 -1883 (Apud J.H. Schubothium, 1821)

Ornithological bibliography - Coues, Elliott, 1842 -1899 (Geological Survey [etc.], 1878)

Ornithological biography, or an account of the habits of the birds of the United States of America ; accompanied by descriptions of the objects represented in the work entitled The Birds of America, and interspersed with delineations of American scenery and manners - Audubon, John James, 1785 -1851 (Adam Black, 1831)

Ornithological biography, or an account of the habits of the birds of the United States of America ; accompanied by descriptions of the objects represented in the work entitled The Birds of America, and interspersed with delineations of American scenery and manners - Audubon, John James, 1785 -1851 (Adam Black, 1834)