Sham, Sani
Universiti Kebangsaan Malaya, 1980
Buku Teks
Hyde, Richard, author
E & FN Spon, 2000
Buku Teks
Jackson, I.J.
Longman Scientific & Technical, 1993
Buku Teks
Boswell, Michael R., author
Island Press, 2012
eBooks
edited by D.J. Greenland and R. Lal
John Wiley & Sons, 1979
Buku Teks