Hofmann, Karl H., author
VEB Deutscher Verlag, 1973
Buku Teks
Chalofsky, Neal, author
American Society for Training & Development Press, 2001
eBooks
Vira Andalusita Mulyaningrum, author
Fakultas Psikologi Universitas Indonesia, 2016
UI - Skripsi (Membership)
Artikel Jurnal
Lecler S.J., Joseph
Burns Oates & Washbourne, 1952
Buku Teks