MLA

Simpson, Randolph Linsly, 1927-1992. D. Mahan, Pittsburgh, PA Full length portrait, young man standing on steps, left arm on newel post, holding felt hat in right hand, prominent watch chain. Cabinet photograph. Box 9, folder 181. circa 1890. https://collections.library.yale.edu/catalog/2002233.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 9, folder 181"])(circa 1890)[D. Mahan, Pittsburgh, PA Full length portrait, young man standing on steps, left arm on newel post, holding felt hat in right hand, prominent watch chain. Cabinet photograph]. https://collections.library.yale.edu/catalog/2002233.