@article{AMLG_1957__3_137732,
     author = {H. Arnold Schmidt},
     title = {Die {Gesamtheit} der idempotenten implikativen {Modalit\"atenstrukturen.}},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {29--49},
     publisher = {mathdoc},
     volume = {3},
     year = {1957},
     zbl = {0081.01102},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1957__3_137732/}
}