J. Hartmanis. Context-free languages and Turing machine computations. Mathematical aspects of computer science, Proceedings of symposia in applied mathematics, vol. 19, American Mathematical Society, Providence1967, pp. 42–51.
1947 ◽
Vol 53
(7)
◽
pp. 637-639
1962 ◽
Vol 42
(1-2)
◽
pp. 84-84