Sheth, Jagdish N.
Ohio South-Western Pub, 1989
Buku Teks
Bearden, William O.
McGraw-Hill, 2001
Buku Teks
Bearden, William O.
McGraw-Hill, Irwin, 2007
Buku Teks
Bearden, William O.
McGraw-Hill/Irwin, 2004
Buku Teks
Wales, Hugh G.
The University of Illinois Press , 1951
Buku Teks