@article{UM_2011_19_1_a3,
     author = {Calda, Emil},
     title = {D\r{u}kaz, kter\'y se mi l{\'\i}b{\'\i}},
     journal = {U\v{c}itel matematiky},
     pages = {14--15},
     year = {2011},
     volume = {19},
     number = {1},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/item/UM_2011_19_1_a3/}
}