MLA

Darley, James M. (James Morrison), National Geographic Society (U.S.). Cartographic Section. Germany and its approaches : with international boundaries as of September 1, 1939, the day Germany invaded Poland and, in red, boundaries as of January 1, 1938, before Germany seized Austria and Czechoslovakia / compiled and drawn in the Cartographic Sec. BRBL_00121. c1944.. https://collections.library.yale.edu/catalog/15476424.

APA, 6th edition

Darley, James M. (James Morrison), & National Geographic Society (U.S.). Cartographic Section. (["BRBL_00121"])(c1944.)[Germany and its approaches : with international boundaries as of September 1, 1939, the day Germany invaded Poland and, in red, boundaries as of January 1, 1938, before Germany seized Austria and Czechoslovakia / compiled and drawn in the Cartographic Sec]. https://collections.library.yale.edu/catalog/15476424.