Here are some more recent papers that also give good insight into research
in this area:
http://www.cs.usask.ca/~wew036/comprehensive.pdf
http://www.cse.ohio-state.edu/hpcs/WWW/HTML/publications/papers/TR-05-3.pdf
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* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD