@article{CMJ_1998_48_1_a4,
     author = {Junnila, H. J. K. and K\"unzi, H. P. A.},
     title = {Characterizations of absolute $F_{\sigma\delta}$-sets},
     journal = {Czechoslovak Mathematical Journal},
     pages = {55--64},
     year = {1998},
     volume = {48},
     number = {1},
     mrnumber = {1614072},
     zbl = {0926.54018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMJ_1998_48_1_a4/}
}