Williamson, John
New York University Press, 1991
Buku Teks
Williamson, John
Harvester Wheatsheaf, 1991
Buku Teks
Reynold, Lloyds
Richard D. Irwin, 1966
Buku Teks
Torr, Christopher, author
Westview Press, 1988
Buku Teks
Lipsey, Richard G., 1928-, author
Harper Collin, 1996
Buku Teks