@article{PMFA_1957_2_3_a9,
     author = {Dole\v{z}al, V\'aclav},
     title = {O jedn\'e trigonometrick\'e identit\v{e}},
     journal = {Pokroky matematiky, fyziky a astronomie},
     pages = {362--365},
     year = {1957},
     volume = {2},
     number = {3},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/item/PMFA_1957_2_3_a9/}
}