German East Africa. Wilhelmstal. Sheet C.
MLA
Section, Great Britain. War Office. General Staff. Geographical. German East Africa. Wilhelmstal. Sheet C. War Office, 0AD. https://collections.library.yale.edu/catalog/15532751.
APA, 6th edition
Section, G. B. W. O. G. S. G. (0 C.E.). German East Africa. Wilhelmstal. Sheet C. [Maps]. War Office, https://collections.library.yale.edu/catalog/15532751.