MLA

Simpson, Randolph Linsly, 1927-1992. Unknown photographer Triple portrait: chef with knife and iron, young boy, and soldier in uniform seated, backs to table under field tent. Soldier's uniform, pre-WW I. Photographic postcard. Box 25. circa 1910. https://collections.library.yale.edu/catalog/16172729.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 25"])(circa 1910)[Unknown photographer Triple portrait: chef with knife and iron, young boy, and soldier in uniform seated, backs to table under field tent. Soldier's uniform, pre-WW I. Photographic postcard]. https://collections.library.yale.edu/catalog/16172729.