Dubois, Brenda, 1949-, author
Allyn and Boston, 1992
Buku Teks
Dickson, Donald T.
New York Free Press 1998,
Buku Teks
Foster, John, author
Crest Publishing House, 2003
Buku Teks
Coulshed, Veronica, author
Macmillan, 1988
Buku Teks
Haarman, Louann, author
Oxford University Press, 1989
Buku Teks