Taffinder, Paul
Encyclopaedia of management : leadership vol. 1
Crest publishing, 1999
 Buku Referensi
Singh, U.K.
International encyclopaedia of professional management : vol. 1, public relations management
Anmol Publications, 1998
 Buku Referensi
Singh, U.K.
International encyclopaedia of professional management : vol. 2, marketing management
Anmol Publications, 1998
 Buku Referensi
Singh, U.K.
International encyclopedia of professional management Vol. 7, sales management
New Delhi : Anmol Publications, 1998,
 Buku Referensi
Singh, U.K.
International encyclopedia of professional management Vol. 6, financial management
New Delhi : Anmol Publications, 1998,
 Buku Referensi