R. H. Pierce I. Marshall S. J. Goodenough Object-Oriented Design of an Air-Defence Simulator. 114-124 1993 conf/adaEurope/1993 Ada-Europe db/conf/adaEurope/adaEurope1993.html#PierceMG93 http://dx.doi.org/10.1007/3-540-56802-6_10