Williams, Stephen, author
Routledge , 1995
Buku Teks
Adams, John, 1938-, author
Routledge & Kegan Paul, 1981
Buku Teks
Dedi Priadi, author
Universitas Indonesia, 1997
Prosiding
edited by Jo Little, Linda Peake, and Pat Richardson
Macmillan, 1988
Buku Teks
Taylor, Philip E., author
Macmillan, 1953;1948
Buku Teks