1. Tree generating regular systems;Brainerd;Information and Control,1969
2. On certain formal properties of grammars;Chomsky;Information and Control,1959
3. Tree acceptors and some of their applications;Doner;J. of Computer and System Sciences,1970
4. The relation between derivations and syntactical structures in phrase-structure grammars;Eickel;J. Computer System Sci.,1972
5. An axiomatic approach to prefix languages;Gorn,1962