Alan Turing signed pamphlet: Turing’s personal copy of Leventhal & Salkind’s "Spherical Trigonometry", Globe Book Co., New York, 1943;

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Alan Turing signed pamphlet: Turing's personal copy of Leventhal & Salkind's Spherical Trigonometry, Globe Book Co., New York, 1943; signed Alan Turing in red ink on title page, the second ‘a' of ‘Alan' a little blotchy o/w a fine example of his signature and rarely offered. The 53pp pamphlet shows some slight toning to the front cover but is o/w fine and clean internally. The pamphlet focuses on the use of Spherical Trigonometry to pilots and aviators.