1. Lecture Notes in Computer Science;G. Struth,2006
2. Electron. Notes in Theor. Comput. Sci;G. Struth,2001
3. Struth, G.: Canonical Transformations in Algebra, Universal Algebra and Logic. PhD thesis. Inst. für Informatik, Univ. des Saarlandes (1998)
4. Lecture Notes in Computer Science;D.A. Plaisted,1993
5. Kozen, D.: Complexity of finitely presented algebras. Techn. Report TR-76-294, Dept. of Computer Science, Cornell Univ. (1979)