Evans, Peter
Princeton University Press, 1979
Buku Teks
Bryson, George D.
Harper & Brothers, 1961
Buku Teks
Nehrt, Lee Charles, author
Bureau of Business Research, Indiana University, 1970
Buku Teks
Muchlinski, Peter, author
Oxford University Press, 2010
Buku Teks
Beamish, Paul W., 1953-, author
Irwin, 1997
Buku Teks