MLA

Barlow, Joel, 1754-1812. Lafayette, Marie Joseph Paul Yves Roch Gilbert Du Motier, marquis de, to Clara Baldwin, autograph letter, signed. Box 1, folder 16. 1813 August 27. https://collections.library.yale.edu/catalog/17360736.

APA, 6th edition

Barlow, Joel, 1754-1812. (["Box 1, folder 16"])(1813 August 27)[Lafayette, Marie Joseph Paul Yves Roch Gilbert Du Motier, marquis de, to Clara Baldwin, autograph letter, signed]. https://collections.library.yale.edu/catalog/17360736.