@article{AUPO_1986__25_1_a5,
     author = {Vl\v{c}ek, Vladim{\'\i}r},
     title = {On the focal points of solutions of a certain fourth order differential equation},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {97--115},
     publisher = {mathdoc},
     volume = {25},
     number = {1},
     year = {1986},
     mrnumber = {918371},
     zbl = {0643.34040},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_1986__25_1_a5/}
}