@article{10_21136_CPMF_1891_121991,
     author = {P\'anek, Augustin},
     title = {Planimetrick\'e odvozen{\'\i} {Heronova} vzorce pro plosk\'y obsah troj\'uheln{\'\i}ku},
     journal = {\v{C}asopis pro p\v{e}stov\'an{\'\i} matematiky a fysiky},
     pages = {310--311},
     year = {1891},
     volume = {20},
     number = {6},
     doi = {10.21136/CPMF.1891.121991},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CPMF.1891.121991/}
}