{Pacific Electric Railway Co. [incl to/from GEH]; Pacific Geographic Society [Humphrey Read]; Pan American Scientific COngress [José J. Bravo]; Paris Observatory; Const. Parvule; J. Newton Parker; Sir Charles Parsons; Pasadena Association; Pasadena High School and Junior College [Ida E. Hawes]; Pasadena Vocation Bureau [Marion de Paar]; A. W. Pawlow; Fred Pearson; Peckham Bros.; George B. Pegram; Walter M. Pegram; Peking Central Observatory; G. Edward Pendray}
{Karl Bohlin; N. Boneff; M. Thérèse Bonney; Andrew R. Boone; Henry Borsook; H. Bourget [incl ltr GEH ? HB]; Frederick Edward Brasch; Charles Breasted; Virginia Brenton [ltr Helen B. Pryor ? Monroe E. Deutsch; ltr FHS ? MED]; Alfred Brill; British Astronomical Association [W. Alfred Parr]; William Robert Brooks; W. Sterry Brown; Emile Bruguierel; Mrs. Roberdeau Buchanan; George J. Burns}
{Felix M. Perez [Sanchez]; T. P. Perkins; Nicolas Perrakis; C. D. Perrine; Max Petersen; John E. Pfeiffer; Philadelphia Inquirer [John Miller]; "Pinacyanol" [advert from Lucius & Brüning Farbwerke]; Harry Hemley Plaskett; Poggendorff's Biographisch-Literarisches Handwörterbuch; Popular Astronomy; Popular Science Monthly [Sumner Blossom]; M. A. Porcabeuf; J. G. Porter; Potsdam Astrophysical Observatory [H. von Klüber; E. F. Trondlich]; Poulkovo Observatory; N. R. Powley; Poznan Observatory [Joseph Witkowski]; Irwin G. Priest; Henry S. [& Mrs.] Pritchett; S. Procopin; W. S. Prosser; Herbert Putnam; G. P. Putnam's Sons; W. F. Quarrie & Co. [S. E. Farquhar]}
{G. B. Lal; Lancaster Press, Inc. [O. J. Smith, Jr.]; Hugo Landi; R. J. Lang; Sir Joseph Larmor; Jennie B. Lasby; Latvia University Astronomical Observatory, Riga [S. Slaucitajs]; G. Lecointe; H. Lehmann; Lemcke & Buechner; George H. Lepper; Sophia H. Levy; Lick Observatory; Bernhard Liebisch}
