@article{10_4064_ap92_3_1,
     author = {Zhiting Xu},
     title = {Fite and {Kamenev} type oscillation criteria for
 second order elliptic equations},
     journal = {Annales Polonici Mathematici},
     pages = {199--214},
     publisher = {mathdoc},
     volume = {92},
     number = {3},
     year = {2007},
     doi = {10.4064/ap92-3-1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap92-3-1/}
}