@article{PORMA_1979__38_3-4_115385,
     author = {Levi, Sandro},
     title = {Closed mappings are open at a $G_\delta $ set},
     journal = {Portugaliae mathematica},
     pages = {7--9},
     publisher = {mathdoc},
     volume = {38},
     number = {3-4},
     year = {1979},
     mrnumber = {0745228},
     zbl = {0524.54009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1979__38_3-4_115385/}
}