Interface agents: A review of the field
  This paper reviews the origins of interface agents, discusses challenges that exist within the interface agent field and presents a survey of current attempts to find solutions to these challenges. A history of agent systems from their birth in the 1960's to the current day is described, along with the issues they try to address. A taxonomy of interface agent systems is presented, and today's agent systems categorized accordingly. Lastly, an analysis of the machine learning and user modelling techniques used by today's agents is presented. 
Stuart E. Middleton