Praktische Studien an der Familie der Orchideen, nebst Kulturanweisungen und Beschreibung aller schönblühenden tropischen Orchideen - Beer, Johann Georg, 1803 -1873 (Gerold & Sohn, 1854)

Prehistoric Europe : a geological sketch - Darwin, Charles, 1809 -1882 (Edward Stanford, 1881)

Preliminary catalog of Anthophyta and Pteridophyta, reported as growing spontaneously within one hundred miles of New York City - Torrey Botanical Club. (1888)

Preliminary catalogue of Anthophyta and Pteridophyta, reported as growing spontaneously within one hundred miles of New York City - Torrey Botanical Club. (1888)

Preliminary catalogue of indigenous Natal plants - Wood, John Medley, 1827 -1915 ("Natal Mercury" steam printing works, 1894)

A preliminary catalogue of the flora of New Jersey - Britton, Nathaniel Lord, 1859 -1934 (Office of the Survey, 1881)

... A preliminary catalogue of the flora of New Jersey - Britton, Nathaniel Lord, 1859 -1934 (Office of the survey, 1881)

Preliminary catalogue of the flora of West Virginia - Millspaugh, Charles Frederick, 1854 -1923 (1892)

A preliminary catalogue of the flowering plants and higher cryptogams growing without cultivation within thirty miles of Hanover, N.H., to which is appended a list of the vertebrates of the same region - Jesup, Henry G. (Henry Griswold), 1826 -1903 (N.A. McClary, 1882)

Preliminary keys to otoliths of some adult fishes of the Gulf of Alaska, Bering Sea and Beaufort Sea - United States. National Marine Fisheries Service. (Dept. of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, 1979)

Preliminary list of plants growing without cultivation in the vicinity of Manchester, New Hampshire - Batchelder, Frederick William. (Manchester institute of arts and sciences, 1909)

A preliminary list of the plants of New Brunswick - Fowler, James, 1829 -1923 (Ellis, Robertson & Co, 1885)

A preliminary list of the vascular flora of Allegheny County, Pennsylvania - Shafer, John Adolph, 1863 -1918 (Carnegie Institute Museum?, 1901)

A preliminary revision of the Bombyces of America north of Mexico - Dyar, Harrison G. (Harrison Gray), 1866 -1929 (Allen Press?], 1893)

Price list of hardy perennials - Henry G. Gilbert Nursery; Seed Trade Catalog Collection. (United States Nurseries, 1889)

Price list of orchids - Lager & Hurrell (Nursery) (Lager & Hurrell, 1910)

Primae lineae systematis naturæ : nexui naturali omnium evolutionique progressivae per nixus reascendentes superstructi - Gori͡aninov, Pavel Fedorovich, 1796 -1865 (Typis Karoli Krajanis, 1834)

Primitiae florae costaricensis - Durand, Th. (Théophile), 1855 -1912 (Jardin botanique de l'état, 1891)

Primitiae monographiae rosarum : matériaux pour servir à l'histoire des roses - Crépin, François, 1830 -1903 (Impr C. Annoot-Braeckman, 1869)

Principal range plants of the central and southern Rocky Mountains : names and symbols - Nickerson, Mona F. (Rocky Mountain Forest and Range Experiment Station, Forest Service, U.S. Dept. of Agriculture, 1976)

The principles of applied zoology - Wardle, Robert A. (Robert Arnold), 1890 -1974 (Longmans, Greem, and co, 1929)

Principles of soil microbiology - Waksman, Selman A. (Selman Abraham), 1888 -1973 (Williams & Wilkins, 1927)

Prize essay on the natural and economical history of the fishes marine, fluviatile, and lacustrine, of the river district of the Firth of Forth - Parnell, Richard, 1810 -1882 (A. and C. Black, 1838)

Das Problem des Lebens; biologische Studien - Hartmann, Eduard von, 1842 -1906 (H. Haacke, 1906)

The problem of Krakatao as seen by a botanist - Backer, C. A. (Cornelis Andries), 1874 -1963 (The author, 1900)

Proceedings - Essex Institute. (1856)

Proceedings - Dorset Natural History; Archaeological Society.

Proceedings (and Annual Report) of the Holmesdale Natural History Club, Reigate - Holmesdale Natural History Club. (1865)

Proceedings and Transactions of the Croydon Microscopical & Natural History Club - Croydon Microscopical; Natural History Club. (1881)

Proceedings and transactions of the Liverpool Biological Society - Liverpool Biological Society. (The Society, 1893)

Proceedings and transactions of the Natural History Society of Glasgow - Natural History Society of Glasgow. (The Society, 1886)

Proceedings and transactions of the Natural History Society of Glasgow - Natural History Society of Glasgow. (The Society, 1892)

The Proceedings and transactions of the Nova Scotian Institute of Science - Nova Scotian Institute of Science. (Nova Scotian Institute of Science, 1890)

Proceedings and transactions of the Nova Scotian Institute of Natural Science - Nova Scotian Institute of Natural Science. (Nova Scotian Institute of Natural Science, 1879)

Proceedings and transactions of the Royal Society of Canada. Délibérations et mémoires de la Société royale du Canada - Royal Society of Canada. (Société royale du Canada, 1887)

Proceedings and transactions of the Royal Society of Canada. Délibérations et mémoires de la Société royale du Canada - Royal Society of Canada. (Société royale du Canada, 1919)

Proceedings and transactions of the South London Entomological & Natural History Society - South London Entomological; Natural History Society (The Society, 1938)

Proceedings - Cambridge Philosophical Society. Mathematical and physical sciences - Cambridge Philosophical Society. (Cambridge Philosophical Society [etc.], 1900)

Proceedings - Cambridge Philosophical Society. Mathematical and physical sciences - Cambridge Philosophical Society. (Cambridge Philosophical Society [etc.], 1902)

Proceedings - Cambridge Philosophical Society. Mathematical and physical sciences - Cambridge Philosophical Society. (Cambridge Philosophical Society [etc.], 1910)

Proceedings - Dorset Natural History and Archaeological Society - Dorset Natural History; Archaeological Society. (1877)

Proceedings of the Academy of Natural Sciences of Philadelphia - Academy of Natural Sciences of Philadelphia. (Academy of Natural Sciences of Philadelphia, 1861)

Proceedings of the Academy of Natural Sciences of Philadelphia - Academy of Natural Sciences of Philadelphia. (Academy of Natural Sciences of Philadelphia, 1864)

Proceedings of the Academy of Natural Sciences of Philadelphia - Academy of Natural Sciences of Philadelphia. (Academy of Natural Sciences of Philadelphia, 1918)

Proceedings of the Academy of Natural Sciences of Philadelphia - Academy of Natural Sciences of Philadelphia. (Academy of Natural Sciences of Philadelphia, 1913)

Proceedings of the Academy of Natural Sciences of Philadelphia - Academy of Natural Sciences of Philadelphia. (Academy of Natural Sciences of Philadelphia, 1841)

Proceedings of the American Academy of Arts and Sciences - American Academy of Arts; Sciences. (Metcalf and Co, 1865)

Proceedings of the American Academy of Arts and Sciences - American Academy of Arts; Sciences. (Metcalf and Co, 1878)

Proceedings of the American Academy of Arts and Sciences - American Academy of Arts; Sciences. (Metcalf and Co, 1886)

Proceedings of the American Academy of Arts and Sciences - American Academy of Arts; Sciences. (Metcalf and Co, 1893)

Proceedings of the American Academy of Arts and Sciences - American Academy of Arts; Sciences. (Metcalf and Co, 1922)

Proceedings of the American Academy of Arts and Sciences - American Academy of Arts; Sciences. (Metcalf and Co, 1921)

Proceedings of the American Philosophical Society held at Philadelphia for promoting useful knowledge - American Philosophical Society. (American Philosophical Society, 1890)

Proceedings of the American Philosophical Society held at Philadelphia for promoting useful knowledge - American Philosophical Society. (American Philosophical Society, 1903)

Proceedings of the Biological Society of Washington - Smithsonian Institution (Biological Society of Washington, 1892)

Proceedings of the Biological Society of Washington - Smithsonian Institution (Biological Society of Washington, 1960)

Proceedings of the Biological Society of Washington - Smithsonian Institution (Biological Society of Washington, 1959)

Proceedings of the Biological Society of Washington - Smithsonian Institution (Biological Society of Washington, 1980)

Proceedings of the Biological Society of Washington - Smithsonian Institution (Biological Society of Washington, 1987)

Proceedings of the Biological Society of Washington - Smithsonian Institution (Biological Society of Washington, 2001)

Proceedings of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1856)

Proceedings of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1865)

Proceedings of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1874)

Proceedings of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1877)

Proceedings of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1903)

Proceedings of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1921)

Proceedings of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1923)

Proceedings of the Botanical Society of the British Isles - Botanical Society of the British Isles. (1954)

Proceedings of the Botanical Society of the British Isles - Botanical Society of the British Isles. (1965)

Proceedings of the Botanical Society of the British Isles - Botanical Society of the British Isles. (1967)

Proceedings of the Botanical Society of the British Isles - Botanical Society of the British Isles. (1956)

Proceedings of the Bristol Naturalists' Society - Bristol Naturalists' Society (Bristol, England) (Bristol Naturalists' Society, 1877)

Proceedings of the California Academy of Natural Sciences - California Academy of Natural Sciences (The Academy, 1854)

Proceedings of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1896)

Proceedings of the California Academy of Sciences, 4th series - California Academy of Sciences (California Academy of Sciences, 1946)

Proceedings of the California Academy of Sciences, 4th series - California Academy of Sciences (California Academy of Sciences, 1960)

Proceedings of the Cotteswold Naturalists' Field Club - Cotteswold Naturalists' Field Club. (1886)

Proceedings of the Davenport Academy of Natural Sciences - Davenport Academy of Natural Sciences. (Academy of Natural Sciences [etc.], 1867)

Proceedings of the Delaware County Institute of Science - Delaware County Institute of Science. (The Institute, 1908)

Proceedings of the Entomological Society of Washington - Entomological Society of Washington (Entomological Society of Washington, 1892)

Proceedings of the Entomological Society of Washington - Entomological Society of Washington (Entomological Society of Washington, 1893)

Proceedings of the Entomological Society of Washington - Entomological Society of Washington (Entomological Society of Washington, 1908)

Proceedings of the Entomological Society of Washington - Entomological Society of Washington (Entomological Society of Washington, 1919)

Proceedings of the Essex Institute - Essex Institute. (Essex Institute Press, 1856)