Little, Brown and Company , 1998
Buku Teks
Wedgwood, C.V. (Cicely Veronica), 1910-
The British Council by Longmans, Green, 1955
Buku Teks
Hirst, David L., author
Macmillan, 1985
Buku Teks
Geckle, George L.
MacMillan Education, 1988
Buku Teks
Sri Marleni, author
2015
UI - Tesis (Membership)