Greene, Judith
Open University Press, 2006
Buku Teks
Klausmeier, Herbert J.
Harper and Row, 1975
Buku Teks
edited Richard E. Ripple
Harper & Row , 1971
Buku Teks
De Cecco, John P.
Prentice-Hall, 1974
Buku Teks
Stephen N. Elliot [and others]
McGraw-Hill, 2000
Buku Teks