Book excerpt: 2 letters (1 sheet, 1 page each). Letter to J. Duane Upton, Drake Memorial Museum, on printed letterhead of Lee de Forest Laboratories, 5106 Wilshire Boulevard, Los Angeles, 23 December 1940, concerning a manuscript of an article by de Forest titled "The birth of the vacuum tube". Letter to B.E. Tousley, Aerial League of America, on printed letterhead of De Forest Radio Telephone & Telegraph Co., 1391 Sedgwick Avenue, New York, 5 April 1918, concerning the league's recognition of radio engineers in aeronautics. The manuscript (2 sheets, 2 pages), signed at the end by de Forest, referenced in the 1940 letter is included.