Breit, Harvey
The World Pub. Comp., 1956
Buku Teks
Hacker, Diana
Bedford Books of St. Martin?s Press, 1995
Buku Teks
Hirschman, Albert O
The Brookings Institution, 1967
Buku Teks
Breit, William.
Times Mirror/Mosby College Pub., 1986
Buku Teks
Harvey, Greg
IDG Books, 1994
Buku Teks