Damas, David
Ottawa Department of Nothern Affair and national resouces 1963
Buku Teks
Burkowski, Forbes J., author
CRC Press, Taylor & Francis Group, 2009
Buku Teks
Alfonso, Anthony, author
Sophia University LL Center of Applied Linguistics, 1980
Buku Teks
Universitas Indonesia, 2004
UI - Tesis (Membership)
El Naschie, M. S. (Mohammed S.), 1943-, author
McGraw-Hill, 1990
Buku Teks