@article{AMLG_1966__10_137802,
     author = {A. Abian and S. LaMacchia},
     title = {On the existence of an empty set in set-theoretical methods.},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {123--126},
     publisher = {mathdoc},
     volume = {10},
     year = {1966},
     zbl = {0189.28604},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1966__10_137802/}
}