Cunningham, N. E., & Cappel, D. H. (1978). Circular letters of Congressmen to their constituents, 1789-1829. Chapel Hill: Published for the Institute of Early American History and Culture, Williamsburg, Va., by the University of North Carolina Press.

Cunningham, Noble E., and Dorothy Hagberg Cappel. Circular Letters of Congressmen to Their Constituents, 1789-1829. Chapel Hill: Published for the Institute of Early American History and Culture, Williamsburg, Va., by the University of North Carolina Press, 1978.

Cunningham, Noble E., and Dorothy Hagberg Cappel. Circular Letters of Congressmen to Their Constituents, 1789-1829. Chapel Hill: Published for the Institute of Early American History and Culture, Williamsburg, Va., by the University of North Carolina Press, 1978.