Slager, Williams
McGraw-Hill,
Buku Teks
Palmer, Barbara C.
Allyn and Bacon, 1994
Buku Teks
Lucas, Michael
Heinemann Educational Books, 1981
Buku Teks
Bielby, Nicholas
Scholastic Publications, 1994
Buku Teks
Heinemann Educational Books, 1981
Buku Teks