edited by Michael Ungar
[Publisher not identified], [Date of publication not identified]
Buku Teks
Kachru, Yamuna, author
Routledge, 2008
Buku Teks
Gillespie, Sheena, author
Allyn and Bacon , 1994
Buku Teks
Schneider, Susan C., author
Prentice-Hall, 1997
Buku Teks
McGraw-Hill, 2005
Buku Teks