MLA

Section, Great Britain. War Office. General Staff. Geographical. Tcheco-Slovaquie [Cartographic Material] = Czecho-Slovakia. G.S.G.S., 1919. https://collections.library.yale.edu/catalog/15498137.

APA, 6th edition

Section, G. B. W. O. G. S. G. (1919). Tcheco-Slovaquie [cartographic material] = Czecho-Slovakia. [Topographic maps]. G.S.G.S., https://collections.library.yale.edu/catalog/15498137.