Ian Beardwell, Len Holden
Prentice-Hall, 2001
Buku Teks
Greer, Charles R., author
Prentice-Hall, 2001
Buku Teks
Sage Publications, 1995
Buku Teks
Mike Millmore, Philip Lewis, Mark Saunders, Adrian Thornhill, Trevor Morrow
Prentice-Hall, 2007
Buku Teks
by John H. Hollenbeck [and others]
McGraw-Hill, 2009
Buku Teks