[Correspondence] 1927 February 9-1931 March 2
[Empty envelopes] 1928 December 13-1929 April 29
[Correspondence] 1936 September 2-October 31
[Correspondence] 1936 November 2-December 31
[Correspondence] 1937 May 5-29
[Correspondence] 1938 January 2-31
[Correspondence with Rolf Landshoff] 1936 November 17-1938 January 3
[Correspondence with the National Student Federation of the U.S.A.] 1936 December 11-1937 June 3
[Correspondence with the Harvard Graduate School of Engineering] 1937 February 19-1937 April 10
[Correspondence with the American Committee for Christian German Refugees] 1937 August 20-1938 July 19
[Correspondence with the Institute of the Aeronautical Sciences Inc.] 1938 May 11-1938 October 5
[Correspondence with Sylvain Fleischer] 1938 August 21
[Miscellaneous ephemera] ca. 1936-1938
Zentralblatt fuer Geophysik, Meteorologie und Geodaesie (Berlin) ca. 1937