Berry, Ralph, author
London : ROUTLEDGE, 1994,
Buku Referensi
Evans, David, author
Melbourne University Press, 2002
Buku Teks
Berry, Ralph, author
Routledge, 1994
Buku Teks
Purves, Alan C. (Alan Carroll), 1931-1996, author
Harcourt Brace Jovanovich, 1984
Buku Teks
Bullis, Douglas
Times Books International , 1999
Buku Teks