edited by William E. Butler
Sijthoff & Noordhoff, 1980
Buku Teks
Heady, Ferrel
Prentice-Hall, 1966
Buku Teks
edited by S.N. Eisenstadt
Little, Brown and Company, 1968
Buku Teks
Gamer, Robert E.
Allyn and Bacon, 1976
Buku Teks
LaPalombara, Joseph
Conference Board, 1977
Buku Teks