Worthington, Ian, 1946-
Prentice-Hall, 2001
Buku Teks
edited by Rendings Fels
West Publishing, 1975
Buku Teks
Reder, Melvin Waren
Columbia University Press , 1947
Buku Teks
Lipsey, Richard G.
Harper Collin, 1996
Buku Teks
Adreson, W. H. Locke
Prentice Hall of India, 1986
Buku Teks