disusun oleh Sofia Rangkuti-Hasibuan ; editor, Nung Atasana
Gramedia Pustaka Utama, 1992
Buku Teks SO
Hutchinson, Tom, 1930-
Cambridge University Press , 1993
Buku Teks SO
Doff, Adrian
Cambridge University Press, 2010
Multimedia
Doff, Adrian
Cambridge University Press, 2010
Multimedia
Macmillan, 1965
Buku Teks SO