1. Context-free like forms for the phrase-structure grammars;Geffert,1988
2. Grammars with context dependency restricted to synchronization;Geffert,1986
3. Some remarks on derivations in general rewriting systems;Griffiths;Inform. and Control,1968
4. Introductrion to Formal Language Theory;Harrison,1978
5. Confluent String Rewriting;Jantzen,1988