MLA

Barrie, J. M. (James Matthew), 1860-1937. Davies, Michael Llewelyn. Box 16, folder 577. 1917 July 2. https://collections.library.yale.edu/catalog/17462844.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 16, folder 577"])(1917 July 2)[Davies, Michael Llewelyn]. https://collections.library.yale.edu/catalog/17462844.