McKeane, Alasdair
Longman, 1994
Buku Teks SO
Dijck, A. van
J.B. Wolters, 1950
Buku Teks
Wilkes, Angela
Chicago: A Division of NTC Pub., 1987,
Buku Referensi
Robertson, Silvia
Hodder & Stoughton, 1994
Buku Teks SO
Peck, Anthony
Macmillan, 1995
Buku Teks SO