American Psychological Association, 2007
Buku Referensi
edited by Howard J. Wiarda, Harvey F. Kline
Westview Press, 2007
Buku Teks
Susana Nuccetelli, Ofelia Schutte, Otavio Bueno
Wiley, 2013
Buku Teks
Crawford, William R., author
Frederick A. Praeger, 1961
Buku Teks
Wynia, Gary W., author
Cambridge University Press , 1984
Buku Teks