On molecular and microscopic science - Somerville, Mary, 1780 -1872 (J. Murray, 1869)

Opalina : its anatomy and reproduction, with a decription of infection experiments and a chronological review of the literature - Metcalf, Maynard M. (Maynard Mayo), 1868 -1940 (G. Fischer, 1909)

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, 1954)

Organisation, systematik und geographisches verhältniss der infusionsthierchen. Zwei vorträge, in der Akademie der wissenschaften zu Berlin gehalten in den jahren 1828 und 1830 - Ehrenberg, Christian Gottfried, 1795 -1876 (Druckerei der Königlichen akademie der wissenschaften, 1830)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1905)

Outlines of evolutionary biology - Dendy, Arthur, 1865 -1925 (D. Appleton and company, 1914)

Outlines of natural history for beginners - Nicholson, Henry Alleyne, 1844 -1899 (Blackwood, 1875)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (Pentland, 1899)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (D. Appleton, 1895)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (H. Frowde and Hodder & Stoughton, 1921)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (D. Appleton, 1906)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (Humphrey Milford, Oxford University Press, 1929)

Oxidation-reduction potentials in bacteriology and biochemistry - Hewitt, L. F. (Williams and Wilkins, 1950)

Parasites : articles contributed to Wood's reference handbook of the medical sciences, new series, 1900-1904 - Ward, Henry Baldwin, 1865 -1945 (1904)

The parasites of man, and the diseases which proceed from them : a text-book for students and practitioners - Leuckart, Rudolf, 1823 -1898 (Young J. Pentland, 1886)

The parasites of man, and the diseases which proceed from them; a textbook for students and practitioners - Leuckart, Rudolf, 1823 -1898 (Pentland, 1886)

The parasitic amoebae of man - Craig, Charles Franklin, 1872 -1950 (J. B. Lippincott Company, 1911)

Parasitology - British Society for Parasitology. (Cambridge University Press, 1908)

Parasitology - British Society for Parasitology. (Cambridge University Press, 1909)

Parasitology (Cambridge University Press, 1918)

Partial syllabic lists of the clinical morphologies of the blood, sputum, feces, skin, urine, vomitus, foods : including potable waters, ice and the air, and the clothing (after Salisbury) - Cutter, Ephraim, 1832 -1917 (The Ariston, 1888)

Pathogenic micro-organisms : including bacteria and Protozoa; a practical manual for students, physicians and health officers - Park, William Hallock, 1863 -1939 (Kimpton, 1908)

Pathogenic micro-organisms; a text-book of microbiology for physicians and students of medicine - MacNeal, Ward J., 1881 -1946 (P. Blakiston's son & co, 1914)

The pathology and differential diagnosis of infectious diseases of animals - Moore, Veranus A. (Veranus Alva), 1859 -1931 (Taylor & Carpenter, 1902)

Pflanzenphysiologie; Versuche und Beobachtungen an böheren und niederen Pflanzen einschliesslich Bakteriologie und Hydrobiologie mit Planktonkunde - Kolkwitz, R. (Richard), 1873 -1956 (G. Fischer, 1922)

Pflügers Archiv für die gesamte Physiologie des Menschen und der Tiere (M. Hager, 1911)

The Philippine journal of science - Philippines. National Science Development Board. (Bureau of Science, 1908)

Physiologische studien - Focke, Gustav Woldemar, 1810 -1877 (C. Schünemann, 1847)

The physiology of plants. a treatise upon the metabolism and sources of energy in plants - Pfeffer, W. (Wilhelm), 1845 -1920 (Clarendon Press, 1900)

The physiology of plants; a treatise upon the metabolism and sources of energy in plants - Pfeffer, W. (Wilhelm), 1845 -1920 (Clarendon press, 1906)

Phytologia - Moldenke, Harold N. (Harold Norman), 1909 -1996 (H.A. Gleason and H.N. Moldenke, 2019)

A picture book of evolution - Hird, Dennis, 1850 -1920 (Watts, 1907)