[zielczynski]
[xp-user-stories]
http://www.extremeprogramming.org/rules/userstories.html : This is the main website for eXtreme Programming (XP), an approach to software development currently popular among practitioners. User stories are commonly used among XP practitioners to capture requirements.
[uml-user-guide]
The Unified Modeling Language User Guide, 2e, G Booch, J Rumbaugh, and I Jacobson