- Two letters from Lysander Spooner to George Bradburn. A two-page note dated June 21, 1845, notifying him that Amasa Walker will be visiting the store of Emerson, Harris & Potter if Bradburn would like to see him. Followed by a one-page letter dated October 17, 1845, notifying him that he must leave Boston to attend to his mother in Athol [Massachusetts]., New-York Historical Society
- 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