Gunther, John, 1901-1970, author
Harper & Brother, 1962
Buku Teks
Europa Publications Limited, 1970
Buku Referensi
Roberts, Geoffrey
Manchester University Press, 1984
Buku Teks
Parker, R. A. C.
Weidenfeld and Nicolson, 1969
Buku Teks
Europa Publications Limited, 1970
Buku Referensi