Gatrell, Caroline, author
McGraw-Hill, 2006
Buku Teks
compiled and edited by M.G. Rao
Discovery Publishing House, 1993
Buku Teks
Alkon Trainindo Utama , 2004
Buku Teks
Sage Publications, 1995
Buku Teks
Gomez-Mejia, Luis R., author
Prentice-Hall, 1995
Buku Teks