@article{AMLG_1987__26_138062,
     author = {A. Abian and K. Keremedis},
     title = {Unramified forcing preserving the law of double negation.},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {177--180},
     publisher = {mathdoc},
     volume = {26},
     year = {1987},
     zbl = {0645.03049},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1987__26_138062/}
}