1. J. Avigad and R. Zach, “The epsilon calculus,” http://plato.stanford.edu/archives/entries/epsilon-calculus/ .
2. F. Baader and W. Snyder, “Unification theory,” in: Handbook of Automated Reasoning, A. Robinson and A. Voronkov (eds.), Elsevier Science Publishers (2001), pp. 447–533.
3. F. Baader and T. Nipkow, Term Rewriting and All That, Cambridge Univ. Press, Cambridge (1999).
4. M. Baaz, “General solutions of equations with variables for substitution,” preprint.
5. M. Baaz and P. Pudlák, “Kreisel’s conjecture for L∃1,” in: Arithmetic Proof Theory and Computational Complexity, P. Clote and J. Krajíček (eds.), Oxford Univ. Press, Oxford (1998), pp. 30–39.