Kalp, E. S., & Morgan, R. M. (1941). Defense of the western hemisphere. Ginn and Company.
Lua i Stíl Chicago (17ú heag.)Kalp, Earl S., agus Robert M. Morgan. Defense of the Western Hemisphere. Boston, New York [etc.]: Ginn and Company, 1941.
Lua MLA (8ú heag.)Kalp, Earl S., agus Robert M. Morgan. Defense of the Western Hemisphere. Ginn and Company, 1941.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.