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