Saxby, H.M., author
Wentworth, 1969
Buku Teks
Cohen, J.M. (John Michael), 1903-1989, author
Penguin Books, 1956
Buku Teks
Evans, Patrick
Penguin Books, 1990
Buku Teks
Richetti, John, author
John Wiley & Sons, 2017
Buku Teks
Sampson, George, author
University Press, 1949
Buku Referensi