1. Openmind indoor commonsense. http://openmind.hri-us.com/, 2010.
2. S. Vasudevan, S. Gächter, R. Siegwart, Cognitive spatial representations for mobile robots perspectives from a user study, in: Proc. ICRA Workshop: Semantic Information in Robotics, ICRA-SIR 2007, 2007.
3. Language and Spatial Cognition;Herskovits,1986
4. Saying, Seeing and Acting: The Psychological Semantics of Spatial Prepositions;Coventry,2003
5. S. Levinson, Language and space, in: Annual Review of Anthropology, 1996.