- Four-page letter dated October 27, 1845, from Lysander Spooner in Athol [Massachusetts] to George Bradburn in Boston, discussing Supreme Court decisions related to slavery, the death of Spooner's mother, and the public reception of his book [The Unconstitutionality of Slavery]., New-York Historical Society
- Four-page letter dated December 26, 1845, from Lysander Spooner in Athol [Massachusetts] to George Bradburn in Boston [Massachusetts], expressing desire to distribute his book [The Unconstitutionality of Slavery] to members of the United States Supreme Court and discussing other opinions on the state of the abolitionist movement., New-York Historical Society
- Six-page letter dated January 7, 1846, from G. [George] Bradburn in Boston [Massachusetts] to Lysander Spooner in Athol, Massachusetts, discussing [Samuel E.] Sewall's criticisms of Spooner's work and also mentioning the acceptance by [Charles?] Allen and "Williams" of Spooner's petition., New-York Historical Society
- Three-page letter dated April 15, 1846, from Geo. [George] Bradburn in Nantucket [Massachusetts] to Lysander Spooner in Athol, Massachusetts, in which he asks for a letter from Dr. and Mrs. [George] Hoyt and discusses Thomas Earle's opinion of Spooner's book [The Unconstitutionality of Slavery]., New-York Historical Society