Christman, J. Richard, author
John Wiley & Sons, 1988
Buku Teks
Blakemore, John Sidney, author
Cambridge Univesity Press, 1985
Buku Teks
Blakemore, John Sidney, author
W.B. Saunders, 1974
Buku Teks
Thomason, Michael, author
Reston Publishing, 1979
Buku Referensi
Elliott, Roger J., author
English Language Book Society, 1978
Buku Teks