Routledge, 1994
Buku Teks
Page, Andrew C., author
Cambridge University Press, 2014
eBooks
Beijer International Institute of Ecological Economics and The World Bank , 1995
Buku Teks
Clark, Frank
Goodyear Publishing Company , 1971
Buku Teks
Fischer, Joel, author
The Free Press, 1994
Buku Teks