Verlag Forschungsinst. f. Mathematikdid.eBooks × Selected Papers from the Annual Conference of Didactics of Mathematics 1996Elektronische Publikation. (http://www.fmd.uni-osnabrueck.de/ebooks/gdm/ annual1996.html)Elmar Cohors-FresenborgForschungsinst. f. Mathematikdid. 1998