Cite

Balkans [cartographic material] : special strategic map compiled by the Army Map Service.

MLA

Service, United States. Army Map. Balkans [Cartographic Material] : Special Strategic Map Compiled by the Army Map Service. Army Map Service, 1943. https://collections.library.yale.edu/catalog/15498773.

APA, 6th edition

Service, U. S. A. M. (1943). Balkans [cartographic material] : special strategic map compiled by the Army Map Service. [Maps]. Army Map Service, https://collections.library.yale.edu/catalog/15498773.