MLA

Barrie, J. M. (James Matthew), 1860-1937. "Notes to accompany sketch for curtain". Box 43, folder 926. 1907. https://collections.library.yale.edu/catalog/32314336.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 43, folder 926"])(1907)["Notes to accompany sketch for curtain"]. https://collections.library.yale.edu/catalog/32314336.