1. H. Andréka, personal communication.
2. H. Andréka, T. Gergely andI. Németi, Purely algebraic constructions of logics,Publications of Central Res. Inst. for Physics, Hungar. Acad. Sci. No. KF-KI-73-71, Budapest, 1973.
3. H. Andréka, T. Gergely andI. Németi, On universal algrebraic constructions of logics,Studia Logica 36 (1977), 9–47.MR 58: 21599
4. H. Andréka, T. Gergely andI. Németi, Model theoretic semantics of many purpose languages and language hierarchies,Proc. Computer Linguistics, COLING '80, Tokyo; 213–219.Zbl 469: 68084
5. H. Andréka, T. Gergely, I. Németi andI. Sain, Theory morphisms, Stepwise refinement of program specifications, Representation of knowledge, and Cylindric algebras, 1980. (Preprint)