MLA

Montagu, Mary Wortley, Lady, 1689-1762. James Marshall Osborn collection of poetry manuscripts, [ca. 1500-1900]. Box 4 | Folder P.B. IV / 161-170. Undated. https://collections.library.yale.edu/catalog/10157342.

APA, 6th edition

Montagu, Mary Wortley, Lady, 1689-1762. (["Box 4 | Folder P.B. IV / 161-170"])(Undated)[James Marshall Osborn collection of poetry manuscripts, [ca. 1500-1900]]. https://collections.library.yale.edu/catalog/10157342.