http://www.useit.com/alertbox/20030120.html
http://www.amazon.com/exec/obidos/ISBN%3D155860569X/useitcomusableinA/
http://www.amazon.com/exec/obidos/ISBN=0262621088/useitcomusablein/
http://www.nngroup.com/reports/roi/
http://www.nngroup.com/reports/tips/usertest/
http://www.nngroup.com/reports/tips/recruiting/
http://www.nngroup.com/services/workshops/learnbydoing.html
http://www.nngroup.com/events/tutorials/intro_user_testing.html
http://www.nngroup.com/events/
http://www.useit.com/alertbox/