Spilsbury, Sallie
Cavendish Publishing Limited, 1998
Buku Teks
Belch, George E., author
McGraw-Hill, [date of publication not identified]
Buku Referensi
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 1994
UI - Skripsi (Membership)
Fakultas Ilmu Sosial dan Ilmu Politik Universitas Indonesia, 2012
UI - Skripsi (Open)
Boyd, Harper W., Jr., author
Prentice-Hall, 1967
Buku Teks