MLA

of New York, American Geographical Society. Block Diagram Showing Terrain of the Balkan Peninsula. The American Geographical Society, 0AD. https://collections.library.yale.edu/catalog/15238166.

APA, 6th edition

of New York, A. G. S. (0 C.E.). Block diagram showing terrain of the Balkan Peninsula. [Maps]. The American Geographical Society, https://collections.library.yale.edu/catalog/15238166.