MLA

Simpson, Randolph Linsly, 1927-1992. Unknown photographer Soldier standing in front of board fence, wearing strapped puttees and narrow visored cap, infantry badges. Photographic postcard. Box 25, folder 1037. circa 1910. https://collections.library.yale.edu/catalog/2042474.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 25, folder 1037"])(circa 1910)[Unknown photographer Soldier standing in front of board fence, wearing strapped puttees and narrow visored cap, infantry badges. Photographic postcard]. https://collections.library.yale.edu/catalog/2042474.