Robinson, Colin, author
Nelson, 1971
Buku Teks
Durie, Bruce, author
[publisher not identified], 2001
Buku Teks
Atkinson, Brian, author
Addison - Wesley , 1998
Buku Teks
Czinkota, Michael R., author
The Dryden Press , 1996
Buku Teks
Jucius, Michael J., author
Richard D. Irwin, 1961
Buku Teks