Tryon, D.T.
The Australian National University , 1969
Buku Teks
Oxford University Press, New York
Buku Referensi
Peter Salim, author
Modern English Press, 1991
Buku Referensi
Park, Chris, author
Oxford University Press, 2008
Buku Referensi
Winson, Nicola V., author
Elsevier, 2005
Buku Referensi