Dignen, Bob
English for presentations = Bahasa Inggris untuk presentasi / Bob Dignen
York Associates, 1999
 Buku Teks
English for specific purposes : law
disusun oleh Sofia Rangkuti-Hasibuan ; editor, Nung Atasana
Gramedia Pustaka Utama, 1992
 Buku Teks
Doff, Adrian
English unlimited : elementary e-portfolio DVD-ROM
Cambridge University Press, 2010
 Multimedia
English this way : teacher's manual and key to books 7-12
Macmillan, 1965
 Buku Teks
Doff, Adrian
English unlimited : elementary teacher's DVD-ROM
Cambridge University Press, 2010
 Multimedia