Merrifield, Ralph
The Pitman Pres , 1983
Buku Teks
Stuart, Dorothy Margaret
Methuen & Co. Ltd., 1956
Buku Teks
Longstaffe-Gowan, Todd, author
Yale University Press, 2001
Buku Teks
Langhans, Edward A.
Southern Illinois University Press, 1981
Buku Teks
Rowbottom, Ralph
Heinemann, 1973
Buku Teks