Bateson, FW
Longmans , 1965
Buku Teks
Blamires, Harry, author
Routledge, 1994
Buku Teks
Blamires, Harry, author
Routledge, 1994
Buku Teks
Gwynn, Stephen, author
Macmillan, 1950
Buku Teks
Lawrence, Karen, author
McGraw-Hill Publishing, 1992
Buku Referensi