Gambia.
MLA
Section, Great Britain. General Staff. Geographical. Gambia. Ordnance Survey Office, 1909. https://collections.library.yale.edu/catalog/15533574.
APA, 6th edition
Section, G. B. G. S. G. (1909). Gambia. [Maps]. Ordnance Survey Office, https://collections.library.yale.edu/catalog/15533574.