MLA

Simpson, Randolph Linsly, 1927-1992. Unknown French photographer Soldier with rifle seated on pile of large caliber artillery shells; wears Engineer Corps badge. Photographic postcard. Box 25. circa 1918. https://collections.library.yale.edu/catalog/16172748.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 25"])(circa 1918)[Unknown French photographer Soldier with rifle seated on pile of large caliber artillery shells; wears Engineer Corps badge. Photographic postcard]. https://collections.library.yale.edu/catalog/16172748.