@article{ARM_1979__15_3_a5,
     author = {Svoboda, Karel},
     title = {Contribution to the characterization of the sphere in $E^3$},
     journal = {Archivum mathematicum},
     pages = {171--177},
     publisher = {mathdoc},
     volume = {15},
     number = {3},
     year = {1979},
     mrnumber = {562341},
     zbl = {0435.53003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1979__15_3_a5/}
}