Understanding Computers and Cognition: A New Foundation for Design, Terry Winograd and Fernando Flores. Addison-Wesley, 1987.
My favorite part is the notion of explicit conversations for action: making requests, counter-proposals, etc. (Reviewed Nov., ’02)
![Understanding Computers and Cognition [affiliate link] Understanding Computers and Cognition](http://3.bp.blogspot.com/_PlP3j1NZE9g/SuRRtAgUZpI/AAAAAAAAAK4/_NU1hcPrTAU/s320/cover-FloresWinograd.jpg)