Carpenter, Catrine
McGraw-Hill, 2004
Buku Teks
Rybak, Stephanie
Macmillan, 1985
Buku Teks
Barratt, William B.
Aldine House, 1994
Buku Teks
Whitmarsh, W.F.H.
Longmans, Green, 1960
Buku Teks
Spencer, R.A.
Edward Arnold, [Date of publication not identified]
Buku Teks