MLA

Simpson, Randolph Linsly, 1927-1992. Unknown photographer View of rustic walks and verdure; three white men; sign: "This Park for Whites Only." Photographic postcard. Box 27, folder 1049. circa 1913. https://collections.library.yale.edu/catalog/2005735.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 27, folder 1049"])(circa 1913)[Unknown photographer View of rustic walks and verdure; three white men; sign: "This Park for Whites Only." Photographic postcard]. https://collections.library.yale.edu/catalog/2005735.