@article{10_21136_CPM_1959_117325,
     author = {Havel, V\'aclav},
     title = {\v{R}e\v{s}itelnost rovnice $x+x=a$ v kart\'ezsk\'ych grup\'ach},
     journal = {\v{C}asopis pro p\v{e}stov\'an{\'\i} matematiky},
     pages = {473},
     publisher = {mathdoc},
     volume = {084},
     number = {4},
     year = {1959},
     doi = {10.21136/CPM.1959.117325},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CPM.1959.117325/}
}