@article{AMLG_1982__22_137994,
     author = {E.G.K. L\'opez-Escobar},
     title = {Further applications of ultra-conservative ...-rules.},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {89--102},
     publisher = {mathdoc},
     volume = {22},
     year = {1982},
     zbl = {0535.03030},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1982__22_137994/}
}