MLA

Clésinger-Sand, Solange, 1828-1899. Brétillot, Antoinette. Box 1, folder 12. 1885, undated. https://collections.library.yale.edu/catalog/17444451.

APA, 6th edition

Clésinger-Sand, Solange, 1828-1899. (["Box 1, folder 12"])(1885, undated)[Brétillot, Antoinette]. https://collections.library.yale.edu/catalog/17444451.