Artikel Jurnal
Staff of Research and Education Association; M. Fogiel, director
Research and Education Association, 1991
Buku Teks
edited by Mihkel Koel
Taylor & Francis Group, 2009
Buku Teks
Entelis, S.G., author
John Wiley & Sons, 1976
Buku Teks
Diana Oetomo, author
Fakultas Psikologi Universitas Indonesia, 2009
UI - Tesis (Open)