G. Sierra, and J. McNaught. International Conference on Computational Intelligence, page 113-116. International Computational Intelligence Society, (2004)
E. Fund, F. of the Earth, N. Society, N. Federation, and S. Club. (1994)Statement of Bruce M. Rich before the Subcommittee on International Economic Policy, Trade, Oceans and Environment, Committee on Foreign Relations, United States Senate, March 3.