@article{10_21136_CMJ_1967_100798,
     author = {Kart\'ak, Karel},
     title = {On {Carath\'eodory} operators},
     journal = {Czechoslovak Mathematical Journal},
     pages = {515--519},
     publisher = {mathdoc},
     volume = {17},
     number = {4},
     year = {1967},
     doi = {10.21136/CMJ.1967.100798},
     mrnumber = {0220999},
     zbl = {0189.39901},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1967.100798/}
}