@article{CulikFris_1977,
    doi = {10.1016/s0019-9958(77)90512-5},
    url = {https://doi.org/10.1016%2Fs0019-9958%2877%2990512-5},
    year = {1977},
    month = {sep},
    publisher = {Elsevier {BV}},
    volume = {35},
    number = {1},
    pages = {20--39},
    author = {K. Culik and I. Fris},
    title = {The decidability of the equivalence problem for {DOL}-systems},
    journal = {Information and Control}
}

@article{CulikFris_1977, doi = {10.1016/s0019-9958(77)90512-5}, url = {https://doi.org/10.1016%2Fs0019-9958%2877%2990512-5}, year = {1977}, month = {sep}, publisher = {Elsevier {BV}}, volume = {35}, number = {1}, pages = {20--39}, author = {K. Culik and I. Fris}, title = {The decidability of the equivalence problem for {DOL}-systems}, journal = {Information and Control} }