@article{AMLG_1970__13_137833,
     author = {H.B. Enderton},
     title = {The unique existential quantifier.},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {52--54},
     publisher = {mathdoc},
     volume = {13},
     year = {1970},
     zbl = {0272.02019},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1970__13_137833/}
}