1. MathSciNet: http://ams.mathematik.uni-bielefeld.de/mathscinet
2. Axiom: http://www.nag.co.uk/symbolic_software.asp
3. L. Babai: Transparent Proofs and Limits to Approximation. Pages 31–91 in Proc. First European Congress of Mathematics. Progress in Math., vol. 199. Birkhäuser, 1994
4. C. Ballarin, K. Homann, J. Calmet: Theorems and Algorithms: An Interface between Isabelle and Maple. Pages 150–157 in A. Levelt (editor), Proceedings of International Symposium on Symbolic and Algebraic Computation (ISSAC’95), ACM Press, 1995
5. H. P. Barendregt: Lambda Calculi with Types. Pages 117–309 in Handbook of Logic in Computer Science, Vol. 2, Oxford University Press, New York, 1992