Ryan, N.J
Oxford University Press, 1970
Buku Teks
Teo, Yi-Ling
Sweet & Maxwell Asia, 2011
Buku Teks
Perry, Martin
Chichester: John Wiley & Sons, c1997
Buku Teks SO
Lee, Sheng-Yi
Singapore University Press, 1974
Buku Teks
Hammond, John Lawrence, 1872-1949
Methuen, 1952
Buku Teks