Thorn, Heinz
National Textbook Company , 1993
Buku Teks
McKeane, Alasdair, author
Longman, 1994
Buku Teks
Wilkes, Angela
Chicago: A Division of NTC Pub., 1987,
Buku Referensi
Dijck, A. van, author
J.B. Wolters, 1950
Buku Teks
Coggle, Paul, author
Kesaint Blanc, 2011
Buku Teks