On the equality sets for homomorphisms on free monoids with two generators K. Culik II; J. Karhumäki — 1980 RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications
On the equivalence of compositions of morphisms and inverse morphisms on regular languages J. Karhumäki; H. C. M. Kleijn — 1985 RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications
On continuous functions computed by finite automata D. Derencourt; J. Karhumäki; M. Latteux; A. Terlutte — 1994 RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications