Edson, Gary
Routledge, 1996
Buku Referensi
editor-in-chief, Robert H. Bishop
CRC Press, 2002
Buku Referensi
Maidment, David R., editor in chief
McGraw-Hill, 1993
Buku Referensi
edited by Michael Rines
Gower in Association with Marketing Magazine, 1981
Buku Teks SO
Hedgecoe, John
Ebury, 1992
Buku Referensi