@article{10_21136_CPM_1978_108790,
     author = {Svoboda, Karel},
     title = {Some global characterizations of the sphere in $E^4$},
     journal = {\v{C}asopis pro p\v{e}stov\'an{\'\i} matematiky},
     pages = {391--399},
     publisher = {mathdoc},
     volume = {103},
     number = {4},
     year = {1978},
     doi = {10.21136/CPM.1978.108790},
     mrnumber = {512236},
     zbl = {0402.53001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CPM.1978.108790/}
}