(1) Correspondence regarding various American observatories, 1959-1963, including correspondence with the United States Naval Observatory, Washington; Thornton Page, Van Vleck Observatory, Wesleyan University, Connecticut; William Liller, Dr H. Shapley, Professor Donald H. Menzel and Professor Leo Goldberg, Harvard College Observatory; Peter van de Kamp, Sproul Observatory, Swarthmore, Pennsylvania; Dr I. King, University of Illinois Observatory; Dr Olin J. Eggen, Mount Wilson and Mount Palomar Observatories; Dr K. Hujer, Department of Astronomy, University of Chattanooga, Tennessee; Dr Henry J. Smith, Sacramento Peak Observatory, New Mexico; High Altitude Observatory, Climax, Colorado; Dr W.J. Luyten, Department of Astronomy, University of Minnesota, Minneapolis; and Miss K. Bracher, John Payson Williston Observatory, Massachusetts.
(2) Correspondence regarding the Lick Observatory, 1960-1962, including correspondence with Dr A. Whitford, Dr H.M. Jeffers and C.D. Shane.
(3) Correspondence regarding the Mount Palomar and Mount Wilson Observatories, 1960-1963, including correspondence with Dr O.C. Wilson, Professor O.J. Eggen, Professor J.L. Greenstein and Dr A.R. Sandage.