Howitt, Dennis, author
Routledge, 2000
Buku Teks
Cohen, Ronald Jay, author
McGraw-Hill, 2005
Buku Teks
Cattell, Raymond B., author
World Book, 1957
Buku Klasik
Games, Paul A., author
McGraw-Hill, 1967
Buku Teks SO
Rasch, Dieter, author
John Wiley & Sons, 2011
Buku Teks