Ingpen, Robert
Dragon's World, 1993
Buku Referensi
Dummer, Geoffrey William Arnold
Pergamon Press, 1983
Buku Teks SO
Eisen, Jonathan
Ufuk Press, 2010
Buku Teks SO
Oxford University press , 1994
Buku Teks
Wilkes, G. A. (Gerald Alfred), 1927-
Fortana/Collins, 1980
Buku Referensi