Hancock, Betsy Ledbetter
Prentice-Hall, 1982
Buku Teks
Coulshed, Veronica
Macmillan, 1988
Buku Teks
Loewenberg, Frank
F.E. Peacock Publishers, Inc, 1988
Buku Teks
Healy, Karen
Palgrave Macmillan, 2005
Buku Teks
Klenk, Robert W.
Wadsworth, 1974
Buku Teks