@article{Hella_1996,
    doi = {10.1006/inco.1996.0070},
    url = {https://doi.org/10.1006%2Finco.1996.0070},
    year = {1996},
    month = {aug},
    publisher = {Elsevier {BV}},
    volume = {129},
    number = {1},
    pages = {1--19},
    author = {Lauri Hella},
    title = {Logical Hierarchies in {PTIME}},
    journal = {Information and Computation}
}

@article{Hella_1996, doi = {10.1006/inco.1996.0070}, url = {https://doi.org/10.1006%2Finco.1996.0070}, year = {1996}, month = {aug}, publisher = {Elsevier {BV}}, volume = {129}, number = {1}, pages = {1--19}, author = {Lauri Hella}, title = {Logical Hierarchies in {PTIME}}, journal = {Information and Computation} }