Crum, Leonard William
National Bureau of Economic Research , 1942
Buku Teks
Crum, William Leonard
University of California Press, 1953
Buku Teks
Maynard, Lee
New York Washington Square Press 1988
Buku Teks
Usry, Milton F., author
Erlangga, 1986
Buku Teks
Hammer, Lawrence H., author
South-Western Pub. Co, 1994
Buku Teks