Cite

Unknown photographer Half length informal portrait of a man wearing a convention badge reading: "Sunday School and B.Y.P.U. Congress." Photographic postcard

MLA

Simpson, Randolph Linsly, 1927-1992. Unknown photographer Half length informal portrait of a man wearing a convention badge reading: "Sunday School and B.Y.P.U. Congress." Photographic postcard. Box 27. circa 1910. https://collections.library.yale.edu/catalog/2057845.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 27"])(circa 1910)[Unknown photographer Half length informal portrait of a man wearing a convention badge reading: "Sunday School and B.Y.P.U. Congress." Photographic postcard]. https://collections.library.yale.edu/catalog/2057845.