Gunn, Thomas Butler. "Diaries, Vol. 5." Diaries, Vol. 5. Missouri History Museum. (1852-1-1).
WORKS ABOUT - Seymour, Charles
Gunn, Thomas Butler. "Diaries, Vol. 6." Diaries, Vol. 6. Missouri History Museum. (1853-1-1).
Gunn, Thomas Butler. "Diaries, Vol. 8." Diaries, Vol. 8. Missouri History Museum. (1856-1-1).
"Literary Intelligence: Literary Conflict - Rejoinder." American Publishers' Circular and Literary Gazette. (1858-3-13).
"The Diamond Lens Controversy." New York Times. (1858-3-15).
"Last Words on the Diamond Lens Controversy." New York Times. (1858-3-19).
Gunn, Thomas Butler. "Diaries, Vol. 11." Diaries, Vol. 11. Missouri History Museum. (1859-1-1).
Quelqu'un [Winter, William]. "Dramatic Feuilleton." New York Saturday Press. (1859-3-26).
Clare, Ada.. "Matilda Heron in 'Geraldine'." New-York Saturday Press. (1859-8-27).
Gunn, Thomas Butler. "Diaries, Vol. 13." Diaries, Vol. 13. Missouri History Museum. (1860-1-1).
[Clapp, Henry Jr. and Robert W. Pearsall]. "Waifs from Washington VII. Typ-orthography." New York Saturday Press. (1860-1-21).
Belphegor. "Dramatic Feuilleton." New York Saturday Press. (1865-12-12).
"[Editorial Comments]." New York Saturday Press. (1865-12-19).
Figaro [Clapp, Henry Jr.]. "Dramatic Feuilleton." New York Saturday Press. (1866-1-13).
Figaro [Clapp, Henry Jr.]. "Dramatic Feuilleton." New York Saturday Press. (1866-1-16).
Browne, Junius Henri. The Great Metropolis; A Mirror of New York. Hartford: American Publishing. (1869-1-1).
"Literary News." The Literary World. (1873-5-11).
"Obituary: Henry Clapp." The New-York Times. (1875-4-11).
Wilson, James Grant and John Fiske. Appletons' Cyclopaedia of American Biography, Volume V, Pickering-Sumter. New York: D. Appleton & Co. (1888-1-1).
Rawson, A. L.. "A Bygone Bohemia." Frank Leslie's Popular Monthly. (1896-1-1).