@techreport {TR-1987-003,
   type = {Technical Report},
   author = {P. Thyagarajan, Arthur M. Farley },
   title = {Design and Implementation of a Qualitative Constraint Satisfaction System },
   institution = {University of Oregon, Computer and Information Sciences Department},
   number = TR-1987-003,
   month = 3,
   year = 1987,
   note = {Available at \url{https://www.cs.uoregon.edu/Reports/TR-1987-003.pdf}},
}