@article{AMLG_1975__17_137912,
     author = {E. B\"orger and Klaus Heidler},
     title = {Die {m-Grade} logischer {Entscheidungsprobleme.}},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {105--112},
     publisher = {mathdoc},
     volume = {17},
     year = {1975},
     zbl = {0362.02025},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1975__17_137912/}
}