Routledge, 2021
eBooks
Seaton, A.V.
International Thomson Businees Press, 1996
Buku Teks
Seaton, A.V.
International Thomson Business Press, 2009
Buku Teks
James Henri
Libraries Unlimited, 2005
Buku Teks
edited by Edward J. Blakely
Human Science Press, 1979
Buku Teks SO