@article{PMFA_1956_1_2_a1,
     author = {Alpert, J. L.},
     title = {Ionosf\'era},
     journal = {Pokroky matematiky, fyziky a astronomie},
     pages = {145--155},
     year = {1956},
     volume = {1},
     number = {2},
     language = {cs},
     url = {http://geodesic.mathdoc.fr/item/PMFA_1956_1_2_a1/}
}