1. B.G. Baumgart: MicroPlanner Alternate Reference Manual. Stanford AI Lab., Operating Note No. 67, Stanford University, April 1972
2. K. Biss, R.T. Chien, F. Stahl, S.J. Weissman: Semantic Modelling for Deductive Question-Answering. IEEE Trans, on Computers, Vol. C-25 (1976), No. 4, S. 358–366
3. F. Black: A Deductive Question Answering System. Ph.D. Thesis, Harvard University, Cambridge, 1962, auch in: M. Minsky (ed.): Semantic Information Processing. MIT Press, Cambridge, 1968
4. J.A. Campbell (ed.): Implementations of Prolog. Ellis Horwood, Chichester, 1984
5. D.J.M. Davies: Popler — Implementation of a POP-2-based Planner, in: [4]