"Proposal to Office of Naval Research for Extension of Contract Nonr 401 (27) from December 1, 1961 to June 15, 1962", Nov. 13, 1961, Box: 1, Folder: 4. Arecibo Ionospheric Observatory and Electrical Engineering reports, 16-6-3333. Division of Rare and Manuscript Collections. https://archives.library.cornell.edu/repositories/2/archival_objects/254515 Accessed April 06, 2026.