Haskard, Macolm R.
Prenticel Hall, 1988
Buku Teks
Tal, Daniel, author
John Wiley & Sons, 2009
Buku Teks
Beijer International Institute of Ecological Economics and The World Bank , 1995
Buku Teks
Simonds, John Ormsbee, author
McGraw-Hill, 1983
Buku Teks
Walker, Theodore D., author
John Wiley & Sons, 1991
Buku Teks