Todd C. Wiggen, « Admiral Frederick C. Billard: The Man Who Dramatically Enhanced and Enlarged the Fledgling Coast Guard Intelligence Program », American Intelligence Journal, vol. 35, no 1, , p. 36–40 (ISSN0883-072X, lire en ligne, consulté le )
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Todd C. Wiggen, « Admiral Frederick C. Billard: The Man Who Dramatically Enhanced and Enlarged the Fledgling Coast Guard Intelligence Program », American Intelligence Journal, vol. 35, no 1, , p. 36–40 (ISSN0883-072X, lire en ligne, consulté le )