@article{Valiant_1974,
    doi = {10.1016/s0019-9958(74)90839-0},
    url = {https://doi.org/10.1016%2Fs0019-9958%2874%2990839-0},
    year = {1974},
    month = {jun},
    publisher = {Elsevier {BV}},
    volume = {25},
    number = {2},
    pages = {123--133},
    author = {Leslie G. Valiant},
    title = {The equivalence problem for deterministic finite-turn pushdown automata},
    journal = {Information and Control}
}

@article{Valiant_1974, doi = {10.1016/s0019-9958(74)90839-0}, url = {https://doi.org/10.1016%2Fs0019-9958%2874%2990839-0}, year = {1974}, month = {jun}, publisher = {Elsevier {BV}}, volume = {25}, number = {2}, pages = {123--133}, author = {Leslie G. Valiant}, title = {The equivalence problem for deterministic finite-turn pushdown automata}, journal = {Information and Control} }