Markus Knauff Reinhold Rauh Christoph Schlieder Gerhard Strube Mental Models in Spatial Reasoning. 267-292 1998 conf/spatialCognition/1998 Spatial Cognition http://link.springer.de/link/service/series/0558/bibs/1404/14040267.htm db/conf/spatialCognition/spatialCognition1998.html#KnauffRSS98