Burgess, Peter H.
Graham Brash, 1983
Buku Referensi
Ray, Sibnarayan
Melbourne and Sydney : Thomas Nelson (Austrakia) Ltd., 1966.
Buku Teks
Palmer, Vance
Longman Cheshire, 1981
Buku Teks SO
edited by Gun Lauritzson
Lund University, 1992
Buku Referensi
Toynbee, Arnold J.
Oxford University Press, 1958
Buku Teks