edited by Daniel C. Mattis
World Scientific, 1994
Buku Referensi
Instituto Poligrafico dello Stato, 1974
Buku Teks
Sternberg, Robert J.
APA, 2000
Buku Teks
Thomas Diefenbach
Ritsumeikan Asia Pacific University (APU), 2016
Artikel Jurnal
Brydon, Steven R.
Mayfield Publishing Company, 2000
Buku Teks