Euromonitor International, 2003
Buku Referensi
Johns Hopkins University Press, 1992
Buku Referensi
Budi Waluyo
Universitas Indonesia, 2003
UI - Tesis Membership
Dian Dwi Laksani
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2009
UI - Tesis Open
Carnes, W. Stansbury
HarperBusiness, 1992
Buku Referensi