The Academy of Political Science, 1977
Buku Teks
Haydock, Roger S.
West , 1992
Buku Teks
Steinberg, Stephen, author
McGraw-Hill, 1974
Buku Teks
Spaeth, Harold J.
W.H.Freeman and Company, 1976
Buku Teks
edited by Perry Miller
Doubleday, 1962
Buku Teks