Shell, Marc
The Johns Hopkins University Press, 1978
Buku Teks
Robbins, Lionel, editor
McMillan & Co., 1952
Buku Teks
McKenzie, Richard B.
McGraw-Hill, 1978
Buku Teks
Bastiat, Frederick
D. Van Nostrand , 1964
Buku Klasik
Bladen, V.W.
University of Toronto Press, 1959
Buku Klasik