@article{CMUC_1984_25_2_a17,
     author = {Simon, Petr},
     title = {A closed separable subspace not being a retract of $\beta N$},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {364--365},
     year = {1984},
     volume = {25},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1984_25_2_a17/}
}