Lubis, Nathaniel Alfredo Putera
Universitas Indonesia, 2015
UI - Skripsi (Membership)
DeVos, Rich
Gramedia Pustaka Utama, 1995
Buku Teks
Abdullah Gymnastiar
Khas MQ, 2006
Buku Teks
Iwan Suwarsa
MQS Publishing, 2006
Buku Teks
Levine, Stuart R.
Spektrum, 1996
Buku Teks