Lewis, Bermnard
University of Chicago Press, 1988
Buku Teks
Downes, William
Cambridge University Press, 2003
eBooks
New York : Cambridge University Press
Majalah, Jurnal, Buletin
Malmstrom, Jean
Hayden Book Company, 1965
Buku Teks SO
edited by Barrie Thorne, Cheris Kramarae and Nancy Henley
Heinle & Heinle, 1983
Buku Teks