@techreport {TR-1991-008,
   type = {Technical Report},
   author = {Anne Dardenne, Stephen Fickas, Axel van Lamsweerde},
   title = {Goal-directed Concept Acquisition in Requirements Elicitation},
   institution = {University of Oregon, Computer and Information Sciences Department},
   number = TR-1991-008,
   month = 3,
   year = 1991,
   note = {Available at \url{https://www.cs.uoregon.edu/Reports/TR-1991-008.pdf}},
}