Borg, Walter R.
David Mc Kay Co., 1963
Buku Teks
edited by Christina Hughes
Open University Press, 2003
Buku Teks
Allyn and Bacon , 1971
Buku Teks
by Arthur I. Gates [and others]
Macmillan, 1962
Buku Teks
Hoy, Anita Woolfolk, 1947-
Allyn and Bacon, 2004
Buku Teks