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[2] Ginsburg S.:
The mathematical theory of context-free languages. McGraw-Hill, New York 1966.
MR 0211815 |
Zbl 0184.28401
[3] Havel I.: Doctoral thesis. Prague 1967.
[4] Samoilenko L. G.: Doctoral thesis. Kiev 1968 (in Russian).
[5] Самойленко Л. Г.:
Об одном классе. (1968) 2, 102-103.
Zbl 1099.01025