@article{Schmitt_1984,
    doi = {10.1016/s0019-9958(84)80055-8},
    url = {https://doi.org/10.1016%2Fs0019-9958%2884%2980055-8},
    year = {1984},
    month = {may},
    publisher = {Elsevier {BV}},
    volume = {61},
    number = {2},
    pages = {147--158},
    author = {Peter H. Schmitt},
    title = {Diamond formulas: A fragment of dynamic logic with recursively enumerable validity problem},
    journal = {Information and Control}
}

@article{Schmitt_1984, doi = {10.1016/s0019-9958(84)80055-8}, url = {https://doi.org/10.1016%2Fs0019-9958%2884%2980055-8}, year = {1984}, month = {may}, publisher = {Elsevier {BV}}, volume = {61}, number = {2}, pages = {147--158}, author = {Peter H. Schmitt}, title = {Diamond formulas: A fragment of dynamic logic with recursively enumerable validity problem}, journal = {Information and Control} }