MLA

of Strategic Services, United States. Office. Provinces of Kansu and Ninghsia : Board of Economic Warfare / Drawn in R. and A., O.S.S. Office of Strategic Services, 1943. https://collections.library.yale.edu/catalog/15511605.

APA, 6th edition

of Strategic Services, U. S. O. (1943). Provinces of Kansu and Ninghsia : Board of Economic Warfare / drawn in R. and A., O.S.S. [Outline maps]. Office of Strategic Services, https://collections.library.yale.edu/catalog/15511605.