Cite

[Letter to] "Dear T. T." [and signed] "H."

MLA

Tyrwhitt, Sir Thomas, 1763-1833. [Letter to] "Dear T. T." [and signed] "H.". undated. https://collections.library.yale.edu/catalog/2004683.

APA, 6th edition

Tyrwhitt, Sir Thomas, 1763-1833. (undated)[[Letter to] "Dear T. T." [and signed] "H."]. https://collections.library.yale.edu/catalog/2004683.