Sheth, Jagdish N., author
Ohio South-Western Pub, 1989
Buku Teks
Keegan, Warren J., author
Alex Media Komputindo, 1992
Buku Teks
Keegan, Warren J., author
Alex Media Komputindo, 1992
Buku Teks
Perreault, William D., author
Irwin McGraw-Hill, 1999
Buku Teks
Lamont, Douglas, author
Blackwell Publishers, 1996
Buku Referensi