E.Zaleski
Organisation for Economic Cooperation and Development, 1969
Buku Teks
Moore, Barrington
Harvard University Press, 1954
Buku Teks
Spector, Ivar
Van Nostrand Reinhold, 1949
Buku Teks
Stephan, John J.
Stanford University Press, 1994
Buku Teks
Westview Press, 1990
Buku Teks