\begin{thebibliography}{Wielemaker \& Anjewierden, 1992b} \bibitem[Anjewierden, 1992]{PCE:lisp} A.~Anjewierden. \newblock {\em {PCE/Lisp}: {PCE Common Lisp} Interface}. \newblock {SWI}, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands, 1992. \newblock E-mail: anjo@swi.psy.uva.nl. \bibitem[Wielemaker \& Anjewierden, 1992a]{PCE:overview} J.~Wielemaker and A.~Anjewierden. \newblock {\em {PCE-4} Functional Overview}. \newblock {SWI}, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands, 1992. \newblock E-mail: jan@swi.psy.uva.nl. \bibitem[Wielemaker \& Anjewierden, 1992b]{PCE:prolog} J.~Wielemaker and A.~Anjewierden. \newblock {\em Programming in {PCE/Prolog}}. \newblock {SWI}, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands, 1992. \newblock E-mail: jan@swi.psy.uva.nl. \bibitem[Wielemaker, 1992a]{PCE:udc} J.~Wielemaker. \newblock {\em {PCE-4} User Defined Classes Manual}. \newblock {SWI}, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands, 1992. \newblock E-mail: jan@swi.psy.uva.nl. \bibitem[Wielemaker, 1992b]{PCE:draw} J.~Wielemaker. \newblock {\em {PceDraw}: An example of using {PCE-4}}. \newblock {SWI}, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands, 1992. \newblock E-mail: jan@swi.psy.uva.nl. \end{thebibliography}