Cronbach, Lee J
Harper and Row, 1970
Buku Teks
Friedrich, William N., author
Sage Publications, 2001
Buku Teks
Papalia, Diane E., author
AIPI Publication, 2007
Buku Teks
Simeonsson, Rune J., author
Allyn and Bacon, 1986
Buku Teks
Ketut Wirawati, author
2005
UI - Skripsi (Membership)