Shattock, Michael
Open University Press, 2005
Buku Teks
Becker, Esther R.
Harper & Row, 1971
Buku Referensi
Artikel Jurnal
Sri Juni Kuntari
Fakultas Psikologi Universitas Indonesia, 2006
UI - Tesis Membership
Duke, Chris
Open UNiversity Press, 2002
Buku Teks