{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}
{E. Valenta; George Van Biesbroeck; Marguerite Van Biesbroeck; H. C. Van Buskirk; Mabel Van Deusen; E. A. Varela; Ventura Abstract Co. [Charles Barnard]; A. Verschaffel; Vienna II Physical Institute [Georg Stetter]; Vitalait Laboratory, Inc. [Earle L. Ovington]; J. Voute. folded}
{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}
{Leo J. Scanlon; William C. Scarritt; Robert O. Schad; Paul W. Schenck; James A. B. Scherer; Frank H. Schleer; Carl Schleicher & Schüll; Hans W. Schneider; Dorothy E. Schoof; J. Schroeter; F. Schuerer; L. Schützenberger; A. Schwassmann}
{W. H. Havens; Alan S. Hawksworth; E. R. Hedrick; Paul Helbronner; Rollin D. Hemans; St. Hempel; Abel Heywood and Son; "Herschel Portrait" [A. O. Leuschner; Louis J. Carmel]; Elsie Isabel Hill; F. W. Hinrichs, Jr.; Shiu Hirayama; E. Hirsch}
