Lehfeldt, R.A.
Oxford University , 1950
Buku Teks
Chesterman, Andrew
Cambridge University Press, 1991
Buku Teks
Batten,T.R.
Oxford University Press, 1960
Buku Teks
Steven & Sons, 1970
Buku Teks
Peterson, Christopher
W.W. Norton & Company, 1984
Buku Teks