[Autograph letter signed to] an unnamed recipient
MLA
Grenville, Anne (Pitt) Grenville, Lady. [Autograph letter signed to] an unnamed recipient. Folder 6262. 44137. https://collections.library.yale.edu/catalog/9998368.
APA, 6th edition
Grenville, Anne (Pitt) Grenville, Lady. (["Folder 6262"])(44137)[[Autograph letter signed to] an unnamed recipient]. https://collections.library.yale.edu/catalog/9998368.