Washington, George. “From George Washington to The States, 8 June 1783.” University of Virginia Press, Founders Online, National Archives http://founders.archives.gov/documents/Washington/99-01-02-11404.

See also copy at: https://americainclass.org/sources/makingrevolution/independence/text1/washingtoncircularstates.pdf

Referenced by Chapter: Founding Myths by Akhil Reed Amar in Kruse, Kevin M., and Julian E. Zelizer. Myth America: Historians Take On the Biggest Legends and Lies About Our Past. Basic Books, 2023. Location 538-539

Washington had emphasized the need for such an indivisible union—most dramatically in his initial farewell address, a world-famous circular letter to America’s governors in 1783.

Two letters from Henry Sass were published in the Royal Academy along with one of his books you can access these at royal academy online catalogue.