Occasional papers - San Diego Society of Natural History. (San Diego Society of Natural History, 1945)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2009)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2010)

The ocean; a general account of the science of the sea - Murray, John, Sir, 1841 -1914 (Holt, 1913)

Oecology of plants : an introduction to the study of plant-communities - Vahl, M. (Martin), 1749 -1804 (Clarendon Press, 1909)

Oecology of plants : an introduction to the study of plant-communities - Warming, Eugenius, 1841 -1924 (Clarendon Press, 1909)

Oecology of plants; an introduction to the study of plant-communities - Balfour, Isaac Bayley, 1853 -1922 (Clarendon Press, 1909)

The oedogoniaceae; a monograph including all the known species of the genera Bulbochaete, Oedocladium and Oedogonium - Tiffany, L. H. (Lewis Hanford), 1894 -1965 (The author, 1930)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1884)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1886)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1889)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1890)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1891)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1892)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1893)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1900)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1901)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1903)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1904)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1905)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1906)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1907)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1908)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1909)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1910)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1911)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1912)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1913)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1914)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1915)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1916)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1922)

Oesterreichische botanische Zeitschrift (A. Skofitz, 1923)

Die officinellen Pflanzen der Pharmacopoea Germanica für Pharmaceuten und Mediciner besprochen und durch Originalabbildungen erläutert - Kohl, F. G. (Friedrich Georg), 1855 -1910 (Barth, 1895)

Ohio Biological Survey notes - Ohio Biological Survey. (Ohio Biological Survey, 1999)

The Ohio journal of science - Ohio Academy of Science. (Ohio Academy of Science, 1920)

The Ohio naturalist - Ohio Academy of Science. (Biological Club of the Ohio State University, 1906)

L'Oiseau et la Revue francaise d'ornithologie - Société ornithologique de France. (Société ornithologique de France, 1989)

Organography of plants, especially of the Archegoniata and Spermaphyta - Balfour, Isaac Bayley, 1853 -1922 (Clarendon press, 1900)

Organography of plants, especially of the archegoniatae and spermaphyta - Goebel, K. (Karl), 1855 -1932 (Clar. Press, 1900)

The origin and evolution of life, on the theory of action, reaction and interaction of energy - Osborn, Henry Fairfield, 1857 -1935 (C. Scribner's Sons, 1917)

The origin of a land flora : a theory based upon the facts of alternation - Bower, F. O. (Frederick Orpen), 1855 -1948 (Macmillan, 1908)

The origin of a land flora : a theory based upon the facts of alternation - Bower, F. O. (Frederick Orpen), 1855 -1948 (Macmillan and co., limited, 1908)

The origin of a land flora, a theory based upon the facts of alternation - Bower, F. O. (Frederick Orpen), 1855 -1948 (Macmillan and Co., Ltd, 1908)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1911)

Our living resources : a report to the nation on the distribution, abundance, and health of U.S. plants, animals, and ecosystems - United States. National Biological Service. (U.S. Dept. of the Interior, National Biological Service, 1995)

Our native ferns and their allies : with synoptical descriptions of the American Pteridophyta north of Mexico - Underwood, Lucien Marcus, 1853 -1907 (H. Holt, 1896)

Our native ferns and their allies; with synoptical descriptions of the American Pteridophyta north of Mexico - Underwood, Lucien Marcus, 1853 -1907 (H. Holt and company, 1888)

Outlines of classification and special morphology of plants - Balfour, Isaac Bayley, 1853 -1922 (Clarendon Press, 1887)

Outlines of classification and special morphology of plants - Goebel, K. (Karl), 1855 -1932 (Clarendon Press, 1887)