@article{AMLG_1969__12_137827,
     author = {J. Jay Zeman},
     title = {Decision procedures for {S3...} and {S4..} .},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {155--158},
     publisher = {mathdoc},
     volume = {12},
     year = {1969},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1969__12_137827/}
}