1. J. A. Campbell: Implementations of Prolog, Ellis Horwood 1984.
2. J. E. Heaton: CGP User Guide, Technical Report No. 735, Department of Computer Science, Loughborough University of Technology, 1992.
3. J. Sowa: Conceptual Structures, Information Processing in Mind and Machine. Addison-Wesley 1984.
4. P. Kocura, K.K. Ho, D. Moorhouse, G.A. Sharpe: Aspects of Conceptual Graphs Processor Design. In: Proceedings of 6th Annual Workshop on Conceptual Structures. SUNY Binghamton, 11–13 July, 1991, pp.317–329.
5. D.D. Roberts: The Existential Graphs of Charles S. Peirce. The Hague: Mounton 1973.