Holdcroft, David
Butterworth, 1991
Buku Teks
Laski, Harold J., author
George Allen and Unwin, 1952
Buku Teks
Woon, Walter C. M., author
NUS Press (National University of Singapore), 2016
Buku Teks
Strassfeld, Michael, author
Harper and Row, 1985
Buku Referensi
Davies, Howard, author
Butterworth, 1991
Buku Teks