1. P.Rudnicki , An overview of the Mizar project , in Proceedings of the 1992 Workshop on Types for Proofs and Programs , 1992 , pp. 311–330
2. M. M.Wenzel , Isabelle/Isar - A versatile environment for human-readable formal proof documents , Technische Universität München , 2002
3. B.Barras , S.Boutin , C.Cornes , J.Courant , J. C.Filliatre , E.Gimenez , et al. , The Coq proof assistant reference manual: Version 6.1 , Inria , 1997