Cowan, David, author
Cambridge At The University , 1958
Buku Teks
Dobie, Ann B., author
Wadsworth and Cengage Learning, 2012
Buku Teks
Thornborrow, Joanna
New York Routledge , 1998
Buku Teks
Lucy, Niall
Blackwell, 1997
Buku Teks
Eagleton, Clyde
The Ronald Press, 1948
Buku Teks