Economist Books, 1991
Buku Referensi
Wicksell, Knut
George Routledge and Sons , 1946
Buku Teks
Schapiro, J. Salwyn
McGraw-Hill Book Company, Inc., 1950
Buku Teks
Reese, Trevor R.
F.W. Cheshire, 1964
Buku Teks
Kuper, Leo
Vale University Press , 1982
Buku Teks