Observationes Zoologicae : quibus novae complures, aliaeque animalium species describuntur et illustrantur - Hermann, Johannis. (Amandum Koenig, 1804)

Observations on the geology and zoology of Abyssinia, made during the progress of the British expedition to that country in 1867-68 - Blanford, W. T. (William Thomas), 1832 -1905 (Macmillan and co, 1870)

Observations relative to lymphatic hearts - Allison, Joseph J. (E.G. Dorsey, Printer, 1838)

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

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

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1897)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1922)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1973)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1982)

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, 2012)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2013)

Occasional papers of the Museum of Zoology, University of Michigan - University of Michigan. Museum of Zoology. (University of Michigan, 1923)

Odontographie. Vergleichende Darstellung des Zahnsystemes der lebenden und fossilen Wirbelthiere - Giebel, C. (Christoph), 1820 -1881 (A. Abel, 1855)

Odontography : or a treatise on the comparative anatomy of the teeth, their physiological relations, mode of development and microscopic structure, in the vertebrate animals - Owen, Richard, 1804 -1892 (Hippolyte Bailliere, 1840)

Odontography; or, A treatise on the comparative anatomy of the teeth; their physiological relations, mode of development, and microscopic structure, in the vertebrate animals - Owen, Richard, 1804 -1892 (H. Baillière, 1840)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1862)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1869)

Oesterreichisches botanisches Wochenblatt ([L.W. Seidel], 1854)

Oeuvres du comte de Lacépède : comprenant l'histoire naturelle des quadrupèdes ovipares, des serpens, des poissons et des cétacés : accompagnées de 150 planches gravées sur acier, représentant au moins 500 animaux - La Cépède, M. le comte de (Bernard Germain Etienne de La Ville sur Illon), 1756 -1825 (P. Duménil, 1836)

Oeuvres du comte de Lacépède : comprenant l'histoire naturelle des quadrupèdes ovipares, des serpents, des poissons et des cétacés; accompanées du portrait de l'auteur et d'environ 400 figures, exécutés pour cette édition par les meilleurs artistes - Cuvier, Georges, baron, 1769 -1832 (Chez F.D. Pillot, 1832)