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Les oiseaux de l'Europe et leurs oeufs, décrits et dessinés d'après nature - Dubois, Alphonse, 1839 -1921. (chez C. Muquardt, 1872)

Les oiseaux de la province de Que´bec - Dionne, C.-E. (Charles-Eusèbe), 1846 -1925 (Dussault & Proulx, 1906)

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

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

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

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

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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)

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On the power, wisdom, and goodness of God : as manifested in the creation of animals, and in their history, habits, and instincts - Jones, Thomas Rymer, 1810 -1880 (H.G. Bohn, 1853)

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 power, wisdom and goodness of God as manifested in the creation of animals and in their history, habits and instincts - Kirby, William, 1759 -1850 (W. Pickering, 1835)

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The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1895)

The Oölogist for the student of birds, their nests and eggs - Lattin, Frank H. (Frank H. Lattin, 1903)

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, 1918)

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

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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)

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, 1957)

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, 1959)

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

The Oregon naturalist (Naturalist Pub. Co, 1895)

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)

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

Ornis - International Ornithological Committee. (Carl Gerold's Sohn, 1890)