Brown, T. Merritt
Macmillan, 1970
Buku Teks
Sydsaeter, Knut
Prentice-Hall, 1995
Buku Teks
Telser, Lester G.
University of Chicago Press, 1972
Buku Teks
Naylor, Thomas H.
Harcourt, Brace & World, 1969
Buku Teks
Fox, Karl August, 1917-
John Wiley & Sons, 1968
Buku Teks