MLA

Simpson, Randolph Linsly, 1927-1992. Unknown printer "The Cake Walk on the Pier." Minstrel troupe performs outdoors; crowds all around. Postcard. Box 25. circa 1905. https://collections.library.yale.edu/catalog/2005990.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 25"])(circa 1905)[Unknown printer "The Cake Walk on the Pier." Minstrel troupe performs outdoors; crowds all around. Postcard]. https://collections.library.yale.edu/catalog/2005990.