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2. Developmental systems and recursion schemes;Downey,1974
3. Some ET0L languages which are not deterministic;Ehrenfeucht,1973
4. A. Ehrenfeucht and G. Rozenberg, The number of occurrences of letters versus their distribution in some E0L languages, Information and Control, to appear.
5. A. Ehrenfeucht amd G. Rozenberg, A characterization theorem for a subclass of ET0L languages, Acta Informat., to appear.