Cite

Camp Cotton, El Paso, within rifle shot of the line

MLA

Thompson, Paul. Camp Cotton, El Paso, within Rifle Shot of the Line. 1917. https://collections.library.yale.edu/catalog/2015413.

APA, 6th edition

Thompson, P. (1917). Camp Cotton, El Paso, within rifle shot of the line [Photographic postcards, Photographic prints, Photographs]. https://collections.library.yale.edu/catalog/2015413.