MLA

Beinecke, Edwin J. (Edwin John), 1886-1970. Stevenson, Robert, Alan Mowbray (copies). Box 59, folder 1283-1287. 1865-1893, undated. https://collections.library.yale.edu/catalog/16609933.

APA, 6th edition

Beinecke, Edwin J. (Edwin John), 1886-1970. (["Box 59, folder 1283-1287"])(1865-1893, undated)[Stevenson, Robert, Alan Mowbray (copies)]. https://collections.library.yale.edu/catalog/16609933.