Furness, Edna L.
Appleton Century , 1964
Buku Teks
Carney, Edward
Routledge,, 1997
Buku Teks
Basch, Lester D.
Sterling Publishing , 1962
Buku Teks
Mudd, Norma
Hodder & Stoughton Educational , 1998
Buku Teks
Burt, Angela, author
Stanley Thornes, 1995
Buku Referensi