@article{Lisovik_2004,
    doi = {10.1007/s10559-005-0034-7},
    url = {https://doi.org/10.1007%2Fs10559-005-0034-7},
    year = {2004},
    month = {nov},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {40},
    number = {6},
    pages = {939--942},
    author = {L. P. Lisovik and D. A. Koval'},
    title = {Language recognition by two-way deterministic pushdown automata},
    journal = {Cybernetics and Systems Analysis}
}

@article{Lisovik_2004, doi = {10.1007/s10559-005-0034-7}, url = {https://doi.org/10.1007%2Fs10559-005-0034-7}, year = {2004}, month = {nov}, publisher = {Springer Science and Business Media {LLC}}, volume = {40}, number = {6}, pages = {939--942}, author = {L. P. Lisovik and D. A. Koval'}, title = {Language recognition by two-way deterministic pushdown automata}, journal = {Cybernetics and Systems Analysis} }