1. Guan X. , & MacCallum K.J. (1995). Modelling of vague and precise geometric information for supporting the entire design process. In Knowledge Intensive CAD-I, ( Tomiyama T. , Mäntylä & Finger S. , Eds.), Preprints of the 1st IFIPWG5.2 Workshop, pp. 301–319.
2. The Harlequin Group Limited. (1994). Lisp works user's guide.
3. The Electronic Cocktail Napkin—a computational environment for working with design diagrams
4. An introduction to least commitment planning;Weld;Al Magazine,1994