@article{CMH_1979__54_139796,
     author = {Martin Huber and Paul C. Eklof},
     title = {Abelian group extensions and the axiom of constructibility.},
     journal = {Commentarii mathematici Helvetici},
     pages = {440--457},
     publisher = {mathdoc},
     volume = {54},
     year = {1979},
     zbl = {0417.20049},
     url = {http://geodesic.mathdoc.fr/item/CMH_1979__54_139796/}
}