@article{AMLG_1980__20_137963,
     author = {Andreas Blass},
     title = {Conservative extensions of models of arithmetic.},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {85--94},
     publisher = {mathdoc},
     volume = {20},
     year = {1980},
     zbl = {0453.03072},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1980__20_137963/}
}