MLA

American Geographical Society of New York, Briesemeister, William A, Cvijić, Jovan, 1865-1927. Ethnographic map of the Balkan Peninsula / by Jovan Cvijić.. c1918.. https://collections.library.yale.edu/catalog/15238234.

APA, 6th edition

American Geographical Society of New York, & Briesemeister, William A, & Cvijić, Jovan, 1865-1927. (c1918.)[Ethnographic map of the Balkan Peninsula / by Jovan Cvijić.]. https://collections.library.yale.edu/catalog/15238234.