No. 26, Jasin & Umba Valley boundary : map annexed to arrangement between Great Britain and Germany, January, April, 1900 (no. 278, page 921) / Ordnance Survey.
MLA
Survey, Great Britain. Ordnance. No. 26, Jasin & Umba Valley Boundary : Map Annexed to Arrangement between Great Britain and Germany, January, April, 1900 (No. 278, Page 921) / Ordnance Survey. Ordnance Survey?, 1900. https://collections.library.yale.edu/catalog/15532771.
APA, 6th edition
Survey, G. B. O. (1900). No. 26, Jasin & Umba Valley boundary : map annexed to arrangement between Great Britain and Germany, January, April, 1900 (no. 278, page 921) / Ordnance Survey. [Maps]. Ordnance Survey?, https://collections.library.yale.edu/catalog/15532771.
