Hornsby, Beve, author
Heinemann , 1993
Buku Teks
Shepherd, James F., author
Houghton Miffiln, 1984
Buku Teks
Gilbert, Doris W.
Prentice-Hall, 1991
Buku Teks
Blass, Laurie
McGraw-Hill Publishing Company , 1990
Buku Teks
Cunningham, Sarah, author
Oxford University Press, 1994
Buku Teks