@article{Ewald_1986,
    doi = {10.2307/2273953},
    url = {https://doi.org/10.2307%2F2273953},
    year = {1986},
    month = {mar},
    publisher = {Cambridge University Press ({CUP})},
    volume = {51},
    number = {1},
    pages = {166--179},
    author = {W. B. Ewald},
    title = {Intuitionistic tense and modal logic},
    journal = {Journal of Symbolic Logic}
}

@article{Ewald_1986, doi = {10.2307/2273953}, url = {https://doi.org/10.2307%2F2273953}, year = {1986}, month = {mar}, publisher = {Cambridge University Press ({CUP})}, volume = {51}, number = {1}, pages = {166--179}, author = {W. B. Ewald}, title = {Intuitionistic tense and modal logic}, journal = {Journal of Symbolic Logic} }