Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1872)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1873)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1876)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1889)

The Ohio journal of science - Ohio Academy of Science. (Ohio Academy of Science, 1919)

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

The Ohio naturalist - Ohio Academy of Science. (Biological Club of the Ohio State University, 1903)

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

On Cephalozia (a genus of Hepaticae), its subgenera and some allied genera - Spruce, Richard, 1817 -1893 (Printed for the author, 1882)

On the germination, development, and fructification of the higher Cryptogamia : and on the fructification of the Coniferæ - Hofmeister, Wilhelm, 1824 -1877 (Published for the Ray Society, by Robert Hardwicke, 1862)

On the germination, development, and fructification of the higher Cryptogamia, and on the fructification of the Coniferae - Hofmeister, Wilhelm, 1824 -1877 (Pub. for the Ray society by R. Hardwicke, 1862)

Opuscula zoologica - Zoologische Staatssammlung München. (Zoologische Staatssammlung, 1967)

Ordre naturel des oursins de mer et fossiles : avec des observations sur les piquans des oursins de mer, et quelques remarques sur les bélemnites - Klein, Jacob Theodor, 1685 -1759 (Cl. J.B. Bauche, 1754)

Organographie der Pflanzen, insbesondere der Archegoniaten und Samenpflanzen - Goebel, K. (Karl), 1855 -1932 (G. Fischer, 1913)

Organographie der Pflanzen, insbesondere der Archegoniaten und Samenpflanzen - Goebel, K. (Karl), 1855 -1932 (G. Fischer, 1898)

Organographie der Pflanzen, insbesondere der Archegoniaten und Samenpflanzen - Goebel, K. (Karl), 1855 -1932 (G. Fischer, 1915)

Florist's journal (How and Parsons, 1844)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1890)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1892)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1891)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1893)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1897)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1900)

Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) - Leavitt, Robert Greenleaf, 1865 - (American Book Co, 1901)

Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University - Gray, Asa, 1810 -1888 (American Book Co, 1901)

Outlines of botany for the high school laboratory and classroom : (based on Gray's Lessons in botany) - Gray, Asa, 1810 -1888 (American Book Company, 1901)

Outlines of botany : taken chiefly from Smith's Introduction ... For the use of schools and students - Smith, James Edward, 1759 -1828 (Cummings and Hilliard for the author, 1819)

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

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

Outlines of the natural history of Great Britain and Ireland, containing a systematic arrangement and concise description of all the animals, vegetables and fossiles which have hitherto been discovered in these kingdoms - Berkenhout, John, 1730 -1791 (Printed for P. Elmsly (Successor to Mr. Vaillant), 1770)

Palaeontographica (Theodor Fischer, 1875)

Pamietnik Fizyjograficzny (Druk K. Kowalewskiego, 1882)