Palmier, Leslie H.
The Athlone Press, 1969
Buku Teks
Hawkins, Everett D.
Yale University, 1961
Buku Teks
edited by Reinhard Bendix, Seymour Martin Lipset
Free Press, 1953
Buku Teks
edited by Reinhard Bendix and Seymour Martin Lipset
Free Press, 1966
Buku Teks
Heimstra, Norman W.
Brooks/Cole, 1978
Buku Teks