MLA

Schletter, Annie, 1858-1944. Wilde, Oscar. Box 1, folder 31. 1888. https://collections.library.yale.edu/catalog/32459319.

APA, 6th edition

Schletter, Annie, 1858-1944. (["Box 1, folder 31"])(1888)[Wilde, Oscar]. https://collections.library.yale.edu/catalog/32459319.