MLA

Beinecke, Edwin J. (Edwin John), 1886-1970. [Runciman, James?]. Box 75, folder 1850. 1880 February 5. https://collections.library.yale.edu/catalog/16609958.

APA, 6th edition

Beinecke, Edwin J. (Edwin John), 1886-1970. (["Box 75, folder 1850"])(1880 February 5)[[Runciman, James?]]. https://collections.library.yale.edu/catalog/16609958.