@article{Berwanger_2004,
    doi = {10.1007/s00224-004-1147-5},
    url = {https://doi.org/10.1007%2Fs00224-004-1147-5},
    year = {2004},
    month = {sep},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {37},
    number = {6},
    pages = {675--694},
    author = {Dietmar Berwanger and Erich Gr\"adel},
    title = {Fixed-Point Logics and Solitaire Games},
    journal = {Theory of Computing Systems}
}

@article{Berwanger_2004, doi = {10.1007/s00224-004-1147-5}, url = {https://doi.org/10.1007%2Fs00224-004-1147-5}, year = {2004}, month = {sep}, publisher = {Springer Science and Business Media {LLC}}, volume = {37}, number = {6}, pages = {675--694}, author = {Dietmar Berwanger and Erich Gr\"adel}, title = {Fixed-Point Logics and Solitaire Games}, journal = {Theory of Computing Systems} }