@article{Kleene_1938,
    doi = {10.2307/2267778},
    url = {https://doi.org/10.2307%2F2267778},
    year = {1938},
    month = {dec},
    publisher = {Cambridge University Press ({CUP})},
    volume = {3},
    number = {4},
    pages = {150--155},
    author = {S. C. Kleene},
    title = {On notation for ordinal numbers},
    journal = {Journal of Symbolic Logic}
}

@article{Kleene_1938, doi = {10.2307/2267778}, url = {https://doi.org/10.2307%2F2267778}, year = {1938}, month = {dec}, publisher = {Cambridge University Press ({CUP})}, volume = {3}, number = {4}, pages = {150--155}, author = {S. C. Kleene}, title = {On notation for ordinal numbers}, journal = {Journal of Symbolic Logic} }