Whitaker, Arthur P.
Harvard University Press, 1948
Buku Teks
Westview Press, 1980
Buku Teks
Bemis, Samuel Flagg, 1891-1973, author
Harcourt, Brace, 1943
Buku Teks
Hayes, Margaret Daly, author
Westview Press, 1984
Buku Teks
Molineu, Harold, author
Westerview Press, 1990
Buku Teks