A recursive and a grammatical characterization of the exponential-time languages
In: Theoretical Computer Science, Jg. 3.1976 H. 3, S. 61-74Relationships between pushdown automata and tape-bounded turing machines
In: Automata, languages and programming, Jg. 1973, S. 575-583Relationships between pushdown automata with counters and complexity classes
In: Mathematical systems theory, Jg. 9.1975 H. No. 3, S. 248-264The ring machine
In: Computers and artificial intelligence, Jg. 1987, S. 195-208