@article{PORMA_1971__30_1_115140,
     author = {Saalfrank, C.W.},
     title = {Contractibility and a generalization of absolute extensor},
     journal = {Portugaliae mathematica},
     pages = {71--72},
     publisher = {mathdoc},
     volume = {30},
     number = {1},
     year = {1971},
     mrnumber = {0303499},
     zbl = {0226.54014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1971__30_1_115140/}
}