@article{UM_1998_6_4_a5,
     author = {Leischner, Pavel},
     title = {Heron\r{u}v vzorec je\v{s}t\v{e} jednou},
     journal = {U\v{c}itel matematiky},
     pages = {230--233},
     year = {1998},
     volume = {6},
     number = {4},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/item/UM_1998_6_4_a5/}
}