Radcliffe, Sarah
Routledge, 1996
Buku Teks
Crockatt, Richard, author
Routledge, 2003
Buku Teks
Joseph Maier, Richard W.Weatherhead
F. A. Praeger, 1964
Buku Teks
Snow, Peter G.
Holt, Rinehart and Winston, INC, 1967
Buku Teks
edited by Eduardo P. Archetti
MacMillan Education, 1987
Buku Teks