Patrick, John
Macmillan Publishing Company, 1984
Buku Teks
edited by Robert Clayton Pierce
Thomson Learning, 2001
Buku Teks
Commager, Henry Steele, selector
Yale University Press, 1950
Buku Teks
Voice of America Forum Lectures , 1968
Buku Teks
Barnes, Harry Elmer
Prentice-Hall, 1950
Buku Teks