1. Cullingford, R. E. (1986) Natural Language Processing, A knowledge-Engineering Approach. Rownam & Littlefield.
2. Cullingford, R. E. & Joseph, L.J. (1983) A Heuristically ‘Optimal’ Knowledge Base Organization Technique. Automatica, Vo. 19, No. 6
3. Deering, M., Faletti, J. & Wilensky, R. (1981) PEARL-A Package for Efficient Access to Representation in LISP. UCAI-81, Vancouver, British Columbia.
4. Goldman, N. (1975) Conceptual generation. In: R. Schank, Conceptual information processing. Amsterdam: North-Holland.
5. Levelt, W.J.M, & Schriefers, H (1987) Stages of lexical access. In: Gerard Kempen (Ed.) Natural language generation. NATO ASI Series. Martinus Nijhoff Publisher.