MLA

Simpson, Randolph Linsly, 1927-1992. Unknown photographer Oval portrait of young boy in elegant suit, white shirt and tie. Tintype, ninth plate. Box 7, folder 138. 1868. https://collections.library.yale.edu/catalog/2002202.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 7, folder 138"])(1868)[Unknown photographer Oval portrait of young boy in elegant suit, white shirt and tie. Tintype, ninth plate]. https://collections.library.yale.edu/catalog/2002202.