MLA

Corri, Montague, 1784-1849. Autograph letter, signed, to Princess Augusta.. Box 30 | Folder 139. June 13, no year. https://collections.library.yale.edu/catalog/10000204.

APA, 6th edition

Corri, Montague, 1784-1849. (["Box 30 | Folder 139"])(June 13, no year)[Autograph letter, signed, to Princess Augusta.]. https://collections.library.yale.edu/catalog/10000204.