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 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)

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, 1909)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1911)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1922)

Oologia neerlandica : eggs of birds breeding in the Netherlands - Lechner, Arnold Anthon van Pelt (Nijhoff, 1911)

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, 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, 1957)

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)

The Oregon naturalist (Naturalist Pub. Co, 1895)

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, 1890)

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

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1896)

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1895)

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

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1899)

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

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, 1773)

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, 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, 1835)

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, 1838)

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, 1839)

Ornithological dictionary of British birds - Rennie, James, 1787 -1867 (Hurst, Chance, 1831)

Ornithological dictionary of British birds - Rennie, James, 1787 -1867 (W. S. Orr & W. Smith, 1833)

The ornithological guide - Wood, Charles Thorold. (Whittaker, 1835)

An ornithological index, arranged according to the synopsis avium of Mr. Vigors / by T. B. L. Baker - Vigors, N. A.‏ ‎ (Nicholas Aylward),‏ ‎ 1785 -1840 (Printed by R. Taylor, 1835)

[Ornithological papers] - Seebohm, Henry, 1832 -1895 (1876)

Ornithological rambles in Sussex : with a systematic catalogue of the birds of that county, and remarks on their local distribution - Knox, Arthur Edward (J. Van Voorst, 1849)

Ornithological rambles in Sussex : with a systematic catalogue of the birds of that county, and remarks on their local distribution / by A.E. Knox - Knox, Arthur Edward (J. Van Voorst, 1855)

Ornithological report - Yorkshire Naturalists' Union (Yorkshire Naturalists' Union, 1984)

Ornithological report upon collections made in portions of California, Nevada, and Oregon - Henshaw, Henry W. (Henry Wetherbee), 1850 -1930 (1879)

The ornithological works of Arthur, ninth Marquis of Tweeddale - Wardlaw Ramsay, R. G. (Robert George), 1852 -1921 (Taylor and Francis, 1881)