MLA

Great Britain. War Office. General Staff. Geographical Section, United States. Army Map Service. Murmansk Railway. Sheet 4. The Service, 1942. https://collections.library.yale.edu/catalog/15475632.

APA, 6th edition

Great Britain. War Office. General Staff. Geographical Section, U. S. A. M. S. (1942). Murmansk railway. Sheet 4. [Maps]. The Service, https://collections.library.yale.edu/catalog/15475632.