MLA

Simpson, Randolph Linsly, 1927-1992. Unknown photographer Three young children play outdoors near well. Photographic postcard. Box 26. 1906. https://collections.library.yale.edu/catalog/2057836.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 26"])(1906)[Unknown photographer Three young children play outdoors near well. Photographic postcard]. https://collections.library.yale.edu/catalog/2057836.