Williams, Morris, author
Longman, 1972
Buku Teks
Lowenstein, Wendy J., author
Hyland House, 1979
Buku Teks
Andrews, John
University of Sydney , 1973
Buku Teks
George Allen & Unwin Australia, 1981
Buku Teks
Burnley, I. H., author
McGraw-Hill, 1976
Buku Teks