@article{AMLG_1960__5_137754,
     author = {Hugo Ribeiro},
     title = {On the universal completeness of classes of relational systems.},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {90--95},
     publisher = {mathdoc},
     volume = {5},
     year = {1960},
     zbl = {0121.01204},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1960__5_137754/}
}