@article{Ehrich_1971,
    doi = {10.1016/s0019-9958(71)90483-9},
    url = {https://doi.org/10.1016%2Fs0019-9958%2871%2990483-9},
    year = {1971},
    month = {jun},
    publisher = {Elsevier {BV}},
    volume = {18},
    number = {5},
    pages = {404--446},
    author = {R.W. Ehrich and S.S. Yau},
    title = {Two-way sequential transductions and stack automata},
    journal = {Information and Control}
}

@article{Ehrich_1971, doi = {10.1016/s0019-9958(71)90483-9}, url = {https://doi.org/10.1016%2Fs0019-9958%2871%2990483-9}, year = {1971}, month = {jun}, publisher = {Elsevier {BV}}, volume = {18}, number = {5}, pages = {404--446}, author = {R.W. Ehrich and S.S. Yau}, title = {Two-way sequential transductions and stack automata}, journal = {Information and Control} }