Witting, Amy
Penguin Books, 1989
Buku Teks
Witting, Amy
Penguin Books, 1990
Buku Teks
Wittimg, Amy
Penguin Books, 1995
Buku Teks
Nurhasaniah
Universitas Indonesia, 2015
UI - Skripsi (Membership)
Susi Safrina Irawati
Fakultas Psikologi Universitas Indonesia, 2002
UI - Skripsi (Membership)