McCullagh, Marie
Cambridge university press, 2008
Buku Teks
disusun oleh Sofia Rangkuti-Hasibuan ; editor, Nung Atasana
Gramedia Pustaka Utama, 1992
Buku Teks
Macmillan, 1965
Buku Teks
Doff, Adrian
Cambridge University Press, 2010
Multimedia
Doff, Adrian
Cambridge University Press, 2010
Multimedia