@article{Greibach_1967,
    doi = {10.1090/s0002-9939-1967-0209086-1},
    url = {https://doi.org/10.1090%2Fs0002-9939-1967-0209086-1},
    year = {1967},
    publisher = {American Mathematical Society ({AMS})},
    volume = {18},
    number = {2},
    pages = {263--268},
    author = {Sheila A. Greibach},
    title = {A note on pushdown store automata and regular systems},
    journal = {Proceedings of the American Mathematical Society}
}

@article{Greibach_1967, doi = {10.1090/s0002-9939-1967-0209086-1}, url = {https://doi.org/10.1090%2Fs0002-9939-1967-0209086-1}, year = {1967}, publisher = {American Mathematical Society ({AMS})}, volume = {18}, number = {2}, pages = {263--268}, author = {Sheila A. Greibach}, title = {A note on pushdown store automata and regular systems}, journal = {Proceedings of the American Mathematical Society} }