Studie über Postwertzeichen von Peru. By Dr. O. Rommel. München, 1890.
Philippine Islands. The Postage Stamps of the Philippines. By J. M. Bartels, F. A. Foster and F. L. Palmer. Boston, Mass., 1904.
Portugal. Catalogue descriptif et illustré de tous les timbres-poste, &c., du Portugal emis dès 1853 à 1895 avec leur differentes denteleurs, papiers, &c. By T. Ramos. Lisbonne, 1895.
The Dies of the Postage Stamps of Portugal of the Reigns of Dona Maria II. and Dom Pedro V. By R. B. Yardley. Manchester, 1907. ⁂ Thirty plates.
Portugal. Eine Studie über die Ausgaben 1853-76. By L. Berger. Berlin, 1898.
Portuguese Indies. Portuguese India. By G. Harrison and F. H. Napier. London, 1893. ⁂ Two plates.
Prince Edward Island. Prince Edward Island. By R. E. R. Dalwigk. London, 1910.
Prussia. Preussen. By P. Ohrt. Leipzig, 1893-6.
Les Timbres de Prusse. By J. B. Moëns. Bruxelles, 1887.
Reprints. Handbuch aller bekannten Neudrucke staatlicher Postfreimarken, Ganzsachen und Essays. By P. Ohrt. Dusseldorf, 1907.