Illingworth, Ronald S.
Churchill Livingstone, 1987
Buku Teks
Santrock, John W., author
McGraw-Hill, 2001
Buku Teks
Santrock, John W., author
McGraw-Hill, 2006
Buku Teks
Bossard, James H.S., author
Harper & Brothers, 1953
Buku Teks
Steinberg, Laurence, author
Wadsworth and Cengage Learning, 2011
Buku Teks