Lurier, Harold E.
Collier Books,, 1963.
Buku Teks
Dudden, Arthur Power, 1921-
University of Pennsylvania Press, 1963
Buku Teks
Rickard, J.A.
Barnes & Noble, 1952
Buku Teks
Langer, William L.
Houghton Mifflin, 1968
Buku Referensi
McGarry, Daniel D.
Littlefield, Adams, 1968
Buku Teks