1. Andersen, F., Petersen, K.D.: Recursive boolean functions in HOL. In: Archer, M., Joyce, J.J., Levitt, K.N., Windley, P.J. (eds.) Proceedings of the 1991 International Workshop on the HOL Theorem Proving System and its Applications, Davis, August 1991, pp. 367–377. IEEE Computer Society, Silver Spring (1992)
2. Asperti, A., Padovani, L., Coen, C.S., Guidi, F., Schena, I.: Mathematical knowledge management in helm. Ann. Math. Artif. Intell. 38(1–3), 27–46 (2003)
3. LNCS;A Asperti,2004
4. Asperti, A., Coen, C.S., Tassi, E., Zacchiroli, S.: User interaction with the matita proof assistant. J. Autom. Reason. 39, 109–139 (2006)
5. Lecture Notes in Artificial Intelligence;D Aspinall,2006