@article{NSJOM_2008_38_3a_14,
     author = {Z. Petrova},
     title = {Oscillation {Properties} of a {Class} of

 {Second} {Order} {Equations}},
     journal = {Novi Sad Journal of Mathematics},
     pages = {113-119},
     publisher = {mathdoc},
     volume = {38},
     number = {3},
     year = {2008},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2008_38_3a_14/}
}