edited by Jacquetta Hawkes
McGraw-Hill, 1974
Buku Referensi
Feder, Kenneth L.
Mayfield Publishing, 1997
Buku Teks SO
Cambridge University Press, 2009
eBooks
edited by George Houghton
Psychology Press, 2005
Buku Teks SO
by Rob Ranyard [and others]; edited by Rob Ranyard, W. Ray Crozier and Ola Svenson
Routledge , 1997
Buku Teks SO