1. K.K. Al-Taha, R.T. Snodgrass, M.D. Soo: Bibliography on Spatiotemporal Databases, ACM SIGMOD Record, 22(1), March 1993, pp. 59–67.
2. L. Becker, R.H. Güting: Rule-Based Optimization and Query Processing in an Extensible Geometric Database System, ACM TODS 17 (1992), 247–303.
3. L. Becker, R.H. Güting: The GraphDB Algebra: Specification of Advanced Data Models with Second-Order Signature, Informatik-Berichte, No. 183-5/1995, Fernuniversität Hagen, Germany, 1995.
4. L. Becker, A. Voigtmann, K. Hinrichs: Developing Applications with the Object-Oriented GIS-Kernel GOODAC, Bericht 4/96-I, Inst. f. Informatik, WWU Münster, Germany, 1996.
5. E. Clementini, P. DiFelice, P. van Oosterom: A Small Set of Formal Topological Relationships Suitable for End-User Interaction, Proc. SSD'93, LNCS 692, 277–295.