@article{PIM_1991_N_S_49_63_a25,
     author = {M. Ha\v{c}ik and E. Omey},
     title = {On {The} {Zeros} {Of} {Oscillatory} {Solutions} {Of} {Linear} {Second-Order} {Differential} {Equations}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {189 },
     publisher = {mathdoc},
     volume = {_N_S_49},
     number = {63},
     year = {1991},
     url = {http://geodesic.mathdoc.fr/item/PIM_1991_N_S_49_63_a25/}
}