Proceedings of the Royal Irish Academy - Royal Irish Academy. (Royal Irish Academy, 1911)

Proceedings of the Royal Physical Society of Edinburgh - Royal Physical Society of Edinburgh. (The Society, 1874)

Proceedings of the Royal Physical Society of Edinburgh - Royal Physical Society of Edinburgh. (The Society, 1885)

Proceedings of the Royal Society of Edinburgh - Royal Society of Edinburgh. (Royal Society of Edinburgh, 1909)

Proceedings of the Royal Society of Edinburgh - Royal Society of Edinburgh. (Royal Society of Edinburgh, 1915)

Proceedings of the Royal Society of Edinburgh - Royal Society of Edinburgh. (Royal Society of Edinburgh, 1920)

Proceedings of the Royal Society of London - Royal Society (Great Britain) (The Society, 1887)

Proceedings of the Royal Society of London - Royal Society (Great Britain) (The Society, 1899)

Proceedings of the semi-centennial anniversary of the Torrey botanical club, October 18, 19 and 20, 1917 - Torrey Botanical Club. (1918)

Proceedings of the Staten Island Association of Arts and Sciences - Staten Island Association of Arts; Sciences. (The Association, 1906)

Proceedings of the United States National Museum - Smithsonian Institution (Smithsonian Institution Press, [etc.], 1901)

Procès-verbaux - Société Linnéenne de Bordeaux. (1895)

Procès-verbaux - Société Linnéenne de Bordeaux. (1901)

Procès-verbaux - Société Linnéenne de Bordeaux. (1910)

Procès-verbaux - Société Linnéenne de Bordeaux. (1917)

Procès-verbaux - Société Linnéenne de Bordeaux. (1933)

Procès-verbaux - Société Linnéenne de Bordeaux. (1947)

Procès-verbaux - Société Linnéenne de Bordeaux. (1960)

Procès-verbaux - Société Linnéenne de Bordeaux. (1959)

Procès-verbaux - Société Linnéenne de Bordeaux. (1961)

Prodrome d'une histoire des végétaux fossiles - Brongniart, Adolphe, 1801 -1876 (F. G. Levrault, 1828)

Prodrome de la flore belge - Wildeman, E. de (Emile), 1866 -1947 (A. Castaigne, 1898)

Prodrome de la flore corse : comprenant les résultats botaniques de six voyages exécutés en Corse sous les auspices de M. Emile Burnat - Briquet, John, 1870 -1931 (Georg, 1910)

Prodrome de la flore du Grand-Duché de Luxembourg - Koltz, J. P. J. (Jean Pierre Joseph), 1827 -1907 (L. Schamburger, 1873)

Prodromus florae mosquensis - Martius, Heinrich von, 1781 -1831 (In Commercio Industriae, 1817)

Prodromus florae stargardiensis : continens plantas in Ducatu Megapolitano-Stargardiensi S. Strelitzensi sponte provenientes - Schultz, Karl Friedrich, 1765 -1837 (sumtibus C. F. E. Spaethen, 1806)

Prodromus florae veronensis - Goiran, A. (Agostino), 1835 -1909 (1882)

Prof. dr. Thom©♭'s Flora von Deutschland, ©sterreich und der Schweiz in wort und bild f©ơr schule und haus - Thomé, Otto W. (Otto Wilhelm), 1840 -1925 (F. E. K©œhler, 1886)

Prof. dr. Thomé's Flora von Deutschland, Österreich und der Schweiz, in wort und bild, für schule und haus ... mit ... - Migula, W. (Walter), 1863 -1938 (1886)

Prof. dr. Thomé's Flora von Deutschland, Österreich und der Schweiz, in wort und bild, für schule und haus ... mit ... - Migula, W. (Walter), 1863 -1938 (1934)

Progressus rei botanicae = Fortschritte der Botanik = Progrès de la botanique = Progress of botany - Association internationale des botanistes. (G. Fischer, 1911)

Progressus rei botanicae = Fortschritte der Botanik = Progrès de la botanique = Progress of botany - Association internationale des botanistes. (G. Fischer, 1914)

Protected Landscapes: experience around the world. Prepared for the International Symposium on Protected Landscapes, Grange-over-Sands, England 5-10 October 1987 (1987)

The Prothonotary - Buffalo Ornithological Society. (Buffalo Ornithological Society, 1974)

A provisional host-index of the fungi of the United States - Farlow, W. G. (William Gilson), 1844 -1919 (1888)

A provisional host-index of the fungi of the United States - Farlow, W. G. (William Gilson), 1844 -1919 (1891)

A provisional list of the parasitic fungi of Wisconsin - Davis, John Jefferson. (1914)

Pteridologist - British Pteridological Society. (The Society, 1985)

Pteridologist - British Pteridological Society. (The Society, 1987)

Pteridologist - British Pteridological Society. (The Society, 1988)

Pteridologist - British Pteridological Society. (The Society, 1989)

Pteridologist - British Pteridological Society. (The Society, 1990)

Pteridologist - British Pteridological Society. (The Society, 1996)

Pteridologist - British Pteridological Society. (The Society, 1997)

Pteridologist - British Pteridological Society. (The Society, 1998)

Pteridologist - British Pteridological Society. (The Society, 1999)

Pteridologist - British Pteridological Society. (The Society, 2000)

Pteridologist - British Pteridological Society. (The Society, 2001)

Pteridologist - British Pteridological Society. (The Society, 2002)

Pteridologist - British Pteridological Society. (The Society, 2003)

Pteridologist - British Pteridological Society. (The Society, 2004)

Pteridologist - British Pteridological Society. (The Society, 2005)

Pteridologist - British Pteridological Society. (The Society, 2006)

Pteridologist - British Pteridological Society. (The Society, 2008)

Pteridologist - British Pteridological Society. (The Society, 2009)

Pteridologist - British Pteridological Society. (The Society, 2010)

Pteridologist - British Pteridological Society. (The Society, 2011)

Pteridologist - British Pteridological Society. (The Society, 2012)

Pteridologist - British Pteridological Society. (The Society, 2013)

Pteridologist - British Pteridological Society. (The Society, 1984)

Pteridologist - British Pteridological Society. (The Society, 2015)

Pteridologist - British Pteridological Society. (The Society, 2016)

Pteridologist - British Pteridological Society. (The Society, 2017)

Pteridologist - British Pteridological Society. (The Society, 2018)

Pteridologist - British Pteridological Society. (The Society, 2019)

Pteridologist - British Pteridological Society. (The Society, 2020)

Pteridophyta und Anthophyta - Wettstein, Richard, Ritter von Westersheim, 1863 -1931 (K.K. Hof- und Staatsdruckerei, 1908)

Publication. Field Columbian Museum. Botanical series - Field Columbian Museum. (Field Columbian Museum, 1896)

Publication. Field Museum of Natural History. Botanical series - Field Museum of Natural History. (Field Museum of Natural History, 1938)

Pugillus plantarum imprimis Hispanicarum, quas in itinere 1851-52 - Lange, Joh., 1818 -1898 (B. Luno, 1860)

Putney's 1955 garden book - Henry G. Gilbert Nursery; Seed Trade Catalog Collection. (Putney Nursery, 1955)

Quarterly journal of microscopical science (J. and A. Churchill [etc.], 1865)

Quarterly journal of microscopical science (J. and A. Churchill [etc.], 1869)

Quarterly journal of microscopical science (J. and A. Churchill [etc.], 1885)

Quarterly journal of microscopical science (J. and A. Churchill [etc.], 1904)

The Quarterly journal of science (J. Churchill and Sons, etc, 1865)

The Quarterly journal of science (J. Churchill and Sons, etc, 1870)

The Quarterly journal of science (J. Churchill and Sons, etc, 1876)

Quarterly journal of the Florida Academy of Sciences - Florida Academy of Sciences. (Florida Academy of Sciences, 1961)