@techreport {TR-1993-027,
   type = {Technical Report},
   author = {Sarah Douglas },
   title = {LingWorlds: An Intelligent Object-Oriented Environment for Second-Language Tutoring},
   institution = {University of Oregon, Computer and Information Sciences Department},
   number = TR-1993-027,
   month = 12,
   year = 1993,
   note = {Available at \url{https://www.cs.uoregon.edu/Reports/TR-1993-027.pdf}},
}