Lopez, David
St. Paul Minn, 2000
Buku Teks
Bloomer, Aileen, 1947-
Routledge , 2006
Buku Teks
Goatly, Andrew
Routledge , 2000
Buku Referensi
Hurford, James R.
Cambridge University Press, 1993
Buku Teks SO
Hogg, Richard
Cambridge University Press , 1987
Buku Teks SO