@article{10_21136_CMJ_1976_101412,
     author = {Zelinka, Bohdan},
     title = {Self-derived polar graphs},
     journal = {Czechoslovak Mathematical Journal},
     pages = {365--370},
     publisher = {mathdoc},
     volume = {26},
     number = {3},
     year = {1976},
     doi = {10.21136/CMJ.1976.101412},
     mrnumber = {0498290},
     zbl = {0341.05124},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1976.101412/}
}