@article{PMFA_1979_24_4_a7,
     author = {Smullyan, R. M.},
     title = {Matematick\'e h\'adanky},
     journal = {Pokroky matematiky, fyziky a astronomie},
     pages = {212--217},
     year = {1979},
     volume = {24},
     number = {4},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/item/PMFA_1979_24_4_a7/}
}