Lockhart, L.W.
Pustaka Rakjat, 1953
Buku Teks
Bruton, Anthony
Nelson, 1993
Buku Teks
Gilbert, Judy B., author
Cambridge University Press, 2005
Buku Teks
Hornby, Albert Sydney, author
Macmillan, 1951
Buku Teks
Richards, Jack C., author
Cambridge University Press, 1995
Buku Teks