@article{Brzozowski_1978,
    doi = {10.1016/0022-0000(78)90049-1},
    url = {https://doi.org/10.1016%2F0022-0000%2878%2990049-1},
    year = {1978},
    month = {feb},
    publisher = {Elsevier {BV}},
    volume = {16},
    number = {1},
    pages = {37--55},
    author = {J.A. Brzozowski and R. Knast},
    title = {The dot-depth hierarchy of star-free languages is infinite},
    journal = {Journal of Computer and System Sciences}
}

@article{Brzozowski_1978, doi = {10.1016/0022-0000(78)90049-1}, url = {https://doi.org/10.1016%2F0022-0000%2878%2990049-1}, year = {1978}, month = {feb}, publisher = {Elsevier {BV}}, volume = {16}, number = {1}, pages = {37--55}, author = {J.A. Brzozowski and R. Knast}, title = {The dot-depth hierarchy of star-free languages is infinite}, journal = {Journal of Computer and System Sciences} }