1. Formal Languages and Their Relation to Automata;Hopcroft,1969
2. Finite state automata with markets;Kosaraju;Proc. Fourth Annual Princeton Conference on Information Sciences and Systems,1970
3. Regularity preserving functions;Kosaraju;SIGACT News,1974
4. Context-free preserving functions;Kosaraju;Math. Systems Theory,1975
5. A note on prefixes of regular languages;Seiferas;SIGACT News,1974