MLA

Beinecke, Edwin J. (Edwin John), 1886-1970. Photographs of Robert Louis Stevenson with others (In Series III). Box 122, folder 2070-2072. undated. https://collections.library.yale.edu/catalog/2042784.

APA, 6th edition

Beinecke, Edwin J. (Edwin John), 1886-1970. (["Box 122, folder 2070-2072"])(undated)[Photographs of Robert Louis Stevenson with others (In Series III)]. https://collections.library.yale.edu/catalog/2042784.