Abstract
A. Salomaa, “Formal languages”, New York, Academic Press, Inc. (1973).
R. Kurki, Suonio,“A programmer'sintroduction to computabilityand formallanguages” Princeton, N.J., Auerbach Publishers Inc. (1971).
A. V. Abo and J. D. Ullman, “The theory of parsing, translation and compiling” Englewood Cliffs, N.J., Prentice-Hall, Inc. (1972 and 1973).