MLA

Great Britain. War Office. General Staff. Geographical Section, United States. Army Map Service. Caucasia and Neighbouring Territories. Army Map Service, U.S. Army, 1942. https://collections.library.yale.edu/catalog/15475655.

APA, 6th edition

Great Britain. War Office. General Staff. Geographical Section, U. S. A. M. S. (1942). Caucasia and neighbouring territories. [Maps]. Army Map Service, U.S. Army, https://collections.library.yale.edu/catalog/15475655.