1. Fractionally fuzzy grammars with application to pattern recognition;DePalma,1975
2. Recognition of fuzzy languages;Honda,1975
3. F-recognition of fuzzy languages;Honda,1977
4. On the description of fuzzy meaning of context-free languages;Inagaki,1975
5. Codes over languages;Kandel;IEEE Trans. Syst., Man Cybern.,1974