1. A Chomsky hierarchy of isotonic array grammars and languages;Cook;Comput. Graphics and Image Process,1978
2. Introduction to Automata Theory, Languages, and Computation;Hopcroft,1979
3. Array automata and array grammars;Milgram,1972
4. Picture Languages;Rosenfeld,1979
5. An isometric context-free array grammar that generates rectangles;Yamamoto;Trans. IECE Japan,1982