Cite

Lewis, Harriet, autograph letter signed, Galesburg, 7 numbered leaves, with a description of the letter: "What I know about Mark Twain," by Harriet Lewis Paff [q.v.]

MLA

Clemens, Samuel Langhorne, 1835-1910. Lewis, Harriet, autograph letter signed, Galesburg, 7 numbered leaves, with a description of the letter: "What I know about Mark Twain," by Harriet Lewis Paff [q.v.]. Box 1. [1868?] January 10. https://collections.library.yale.edu/catalog/32307878.

APA, 6th edition

Clemens, Samuel Langhorne, 1835-1910. (["Box 1"])([1868?] January 10)[Lewis, Harriet, autograph letter signed, Galesburg, 7 numbered leaves, with a description of the letter: "What I know about Mark Twain," by Harriet Lewis Paff [q.v.]]. https://collections.library.yale.edu/catalog/32307878.