PerfectBound (HarperCollins): http://www.harpercollins.com/hc/perfectbound/
Planet PDF: http://www.planetpdf.com/
Pocket PC: http://www.microsoft.com/mobile/pocketpc/
Poésie d’hier et d’aujourd’hui: http://membres.lycos.fr/mirra/
Presses universitaires de France (PUF): http://www.puf.com/
Prewitt Organizing Fund: http://www.organizingfund.org/
Project Gutenberg: https://www.gutenberg.org/
Psion: http://www.psion.com/
Psion France: http://www.psion-fr.com/
Public Library of Science (PLoS): http://www.publiclibraryofscience.org/