Keylor, William R., 1944-, author
Oxford University Press, 1996
Buku Teks
Palmer, Alan, author
Penguin Books , 1987
Buku Referensi
Shuter, Paul
Heineman Educational , 1988
Buku Teks
Grenville, J.A.S., author
Routledge, 2005
Buku Teks
The University Press of Kentucky, 1972
Buku Teks