@article{CMUC_2011_52_2_a9,
     author = {Protasov, I. V.},
     title = {Coronas of ultrametric spaces},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {303--307},
     year = {2011},
     volume = {52},
     number = {2},
     mrnumber = {2849052},
     zbl = {1240.54087},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_2011_52_2_a9/}
}