1. Amerkad, A., Y. Bertot, L. Pottier and L. Rideau, Mathematics and proof presentation in PCoq, Rapport de Recherche 4313, Inria, Sophia Antipolis (2001)
2. A content based mathematical search engine: Whelp;Asperti,2004
3. Helm and the semantic math-web;Asperti,2001
4. Proof General: A generic tool for proof development;Aspinall,2000
5. Aspinall, D., C. Lüth and D. Winterstein, A framework for interactive proof, in: D. Aspinall, editor, Proceedings of the ETAPS-05 Workshop on User Interfaces for Theorem Provers (UITP-05), Edinburgh, 2005, p. 15, URL: http://proofgeneral.inf.ed.ac.uk/Kit/docs/pgipimp.pdf