{L. Gabba; Galileo Portrait [Charles E. Lewis]; Joaquín Gallo; H. A. Garfield; Willard H. Garrett; G. N. Garrison; General Petroleum Corp. of California; Georgia Astrophysical Observatory; F. Louise Gianetti; Henry L. Giclas; Millicent Gilder}
{Halbert P. Gillette; Curvin H. Gingrich; F. Gonnessiat; Katharine Gordon; W. B. Gordon; Göttingen Observatory/Library; Lucien Gougy; L. Grabowski; Carlos Graef [Fernández]; K. Graff; John Grant; Graphic Arts Press [J. Stuart Lynch]; W. de Groot; George R. Grose; H. Grouiller; Frederick O. Grover [re extra-terrestrial life]; F. A. Guth}
{Science Press; Science Progress; Scientia; Scientific American; Scientific International Research Service Corp.; E. M. Scofield; Charles Scribner's Sons; N. P. Scudder; H. von Seeliger; Seismological Society of America; Selznick International Pictures, Inc. [W. E. McCune]; Service; Geneva Seybold; James A. Shanahan; W. N. Shaw; Barbara Sheffield}
{R. A. Millikan; Monroe Calculating Machine Co. [folded. incl Calculator Equipment Corp.]; Montevideo, Observatory of the University of [folded]; Monthly Weather Review; Joseph Monti; K. Moór [?]; Ernest C. Moore; Morava Construction Co.; D. W. Morehouse [incl ltr H. Shapley ? DWM]; D. P. Moreton; G. W. Morey; --Moriceau; T. H. Morgan; Sylvanus G. Morley; W. D. Morrison; Albert G. Mowbray [incl memo EPH ? FHS]; F. R. Moulton; Z. Müller; Carlos S. Mundt}
{Oberlin College [F. E. Carr; Emma L. Frank]; Sir Frederick O'Connor; J. Ogden; R. M. Ogden; Yngve Öhlman; Eleanor Olney; John Ohlsson; William Tyler Olcott [& G. H. Lutz]; Charles P. Olivier; P. Th. Oosterhoff; Earle L. Ovington}
{Alice H. Farnsworth; Max Farrand; V. L. Fasschel; Anna Mary Felker; Ann Walker [Mrs. James B.] Field; P. H. Field; Howard Finley; John Forsyth; W. E. Forsythe}
{John L. Ridgway; A. E. Riemer; T. K. Riggen; Philip S. Riggs; Augusto Righi; William E. Ritter; G. B. Rizzo; W. F. Roberts Co., Inc. [B. H. Roberts. folded]; H. P. Robertson}
