MLA

Simpson, Randolph Linsly, 1927-1992. C.T. Co., Chicago, [IL] "Caddies of Great Southern Hotel, Gulfport, Miss...." Postcard in color. Box 25, folder 1036. circa 1925. https://collections.library.yale.edu/catalog/32312578.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 25, folder 1036"])(circa 1925)[C.T. Co., Chicago, [IL] "Caddies of Great Southern Hotel, Gulfport, Miss...." Postcard in color]. https://collections.library.yale.edu/catalog/32312578.