Napitupulu, Daniel
2004
Artikel Jurnal
Downes, Colm
Cambridge university press, 2009
Buku Teks
Downes, Colm
Cambridge University Press, 2008
Multimedia
Downes, Colm
Cambridge University Press, 2008
Multimedia
Goldmann, Nahum
McGraw-Hill, 1992
Buku Teks