Longman, 1989
Buku Teks
Shepherd, James F., author
Houghton Miffiln, 1984
Buku Teks
Cunningham, Sarah, author
Oxford University Press, 1994
Buku Teks
Cunningham, Sarah, author
Oxford University Press , 1994
Buku Teks
Yates, Paulene M.
Harper & Row, 1962
Buku Teks