Angela Schwering Kai-Uwe Kühnberger Ulf Krumnack Helmar Gust Spatial Cognition of Geometric Figures in the Context of Proportional Analogies. 18-35 2009 COSIT http://dx.doi.org/10.1007/978-3-642-03832-7_2 conf/cosit/2009 db/conf/cosit/cosit2009.html#SchweringKKG09