Robin, R.H. (Robert Henry)
Longman, 1980
Buku Teks
Bube, Richard H.
Academic Press, 1981
Buku Teks
Waddams, A. Lawrence
The English Language Boook Society and John Murray, , 1968"
Buku Teks
Gray, Alexander
Longmans , 1959
Buku Teks
Clout, hugh D
Pergamon Press, 1977
Buku Teks