1. Lattice Theory;Birkhoff,1967
2. The Mathematical Theory of Context-Free Languages;Ginsberg,1966
3. Morphic congruences and D0L languages;Harrison;Theoret. Comput. Sci.,1994
4. The dynamics of piecewise endomorphisms of finitely-generated free monoids;Harrison,1993
5. Developmental Systems and Languages;Herman,1975