edited by Stephen Ackroyd, Rosemary Batt, Paul Thompson and Pamela S. Tolbert
Oxford University Press, 2006
Buku Referensi
Dubois, Brenda, 1949-
Allyn and Boston, 1992
Buku Teks
Gore, M.S.
Asia Publishing House, 1965
Buku Teks
Cohen, Nathan Edward
National Ass. of Workker, 1964
Buku Teks
Dreitzel, Hans Peter
MacMillan Press , 1971
Buku Teks