@article{10_21136_CPM_1973_108466,
     author = {Kal\'a\v{s}ek, Pavel},
     title = {Pozn\'amka k \v{c}l\'anku {V.} {Petr\r{u}va}},
     journal = {\v{C}asopis pro p\v{e}stov\'an{\'\i} matematiky},
     pages = {156--158},
     publisher = {mathdoc},
     volume = {098},
     number = {2},
     year = {1973},
     doi = {10.21136/CPM.1973.108466},
     mrnumber = {0322110},
     zbl = {0261.26006},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CPM.1973.108466/}
}