Asean -Ec Energy Management Training and Research Centre, 1993,
Buku Referensi
Asia Pacific Economics Group
Jakarta Post, 1996
Buku Teks
Hetherington, John Aikman, 1907-, author
F.W. Cheshire, 1960
Buku Teks
Artikel Jurnal
O`Dowd, Bernard, author
Angust & Robertson, 1963
Buku Teks