Mason, Richard
Fontana/Collins, 1982
Buku Teks
Hutton, Peter, author
APA Publications, 1993
Buku Referensi
Riclefs, M. C.
Allen & Unwin, 1993
Buku Teks
Nada Sakinah, author
Ministry of Energy and Mineral Resources, Jakarta, 2012
Artikel Jurnal
Crelyn, R.J.
"Chichester: John Wiley & Sons, 1990",
Buku Teks