1. Hans-Jürgen Bürckert, Alexander Herold, and Manfred Schmidt-Schauß. On Equational Theories, Unification and Decidability. SEKI-Report SR-86-20, Universität Kaiserslautern, 1986.
2. Hans-Jürgen Bürckert and Manfred Schmidt-Schauß. On the Solvability of Equational Problems. SEKI Report SR-89-07, Universität Kaiserslautern, 1989.
3. Hubert Comon and Pierre Lescanne. Equational problems and disunification. Journal of Symbolic Computation, 7(3,4):371–425, 1989.
4. Hubert Comon. Unification et Disunification. Théorie et Applications. PhD thesis, Institut National Polytechnique de Grenoble, Grenoble, France, 1988.
5. Hubert Comon. Disunification:A Survey. Rapport de Recherche no. 540, LRI, Université de Pairs Sud, january 1990.