Cite

Letter (?copy) to Samuel Hartlib, n.p.

MLA

Letter (?Copy) to Samuel Hartlib, N.p. 1661. https://collections.library.yale.edu/catalog/10033839.

APA, 6th edition

Letter (?copy) to Samuel Hartlib, n.p. (1661). https://collections.library.yale.edu/catalog/10033839.