MLA

Clésinger-Sand, Solange, 1828-1899. Cantilli, General. Box 1, folder 16-18. 1896-1899, undated. https://collections.library.yale.edu/catalog/17444455.

APA, 6th edition

Clésinger-Sand, Solange, 1828-1899. (["Box 1, folder 16-18"])(1896-1899, undated)[Cantilli, General]. https://collections.library.yale.edu/catalog/17444455.