Sethna, Beheruz N.
Tata McGraw-Hill, 1984
Buku Teks
Howard, John A., author
Richard D. Irwin, 1962
Buku Teks
Kotler, Philip, author
[publisher not identified], [date of publication not identified]
Buku Teks
Kotler, Philip, author
Prentice-Hall, 2000
Buku Teks
Wilson, Mike, author
Gower Publishing, 1985
Buku Teks