MLA

Culebra Peak and Range. Looking East from Point about Half Way up San Pedro Mesa at San Luis, Colo. April 9, 1909. 1909. https://collections.library.yale.edu/catalog/2011100.

APA, 6th edition

Culebra Peak and Range. Looking east from point about half way up San Pedro Mesa at San Luis, Colo. April 9, 1909. (1909). [Photographic prints, Photographs]. https://collections.library.yale.edu/catalog/2011100.