1. Cohn, A.G. and S.M. Hazarika, Qualitative Spatial Representation and Reasoning: An Overview. Fundamenta Informaticae, 2001. 46(1–2): p. 1–29.
2. Egenhofer, M.J. and J.R. Herring, Categorizing Binary Topological Relationships Between Regions, Lines, and Points in Geographic Databases. 1991, Department of Surveying Engineering, University of Maine, Orono, ME.
3. Egenhofer, M.J., Deriving the composition of binary topological relations. Journal of Visual Languages and Computing, 1994. 5(1): p. 133–149.
4. Clementini, E. and P. Di Felice, Spatial Operators. ACM SIGMOD Record, 2000. 29(3): p. 31–38.
5. Waller, D., et al., Place learning in humans: The role of distance and direction information. Spatial Cognition and Computation, 2000. 2: p. 333–354.