TY - JOUR AU - Svoboda, Karel TI - Contribution to the characterization of the sphere in $E^3$ JO - Archivum mathematicum PY - 1979 SP - 171 EP - 177 VL - 15 IS - 3 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/ARM_1979__15_3_a5/ LA - en ID - ARM_1979__15_3_a5 ER -