@article{10_4064_ap_6_1_99_104,
     author = {Z. Opial},
     title = {Sur un crit\`ere d'oscillation des int\'egrales de l'\'equation diff\'erentielle {(Q(t)x')'} + f(t)x = 0},
     journal = {Annales Polonici Mathematici},
     pages = {99--104},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {1959},
     doi = {10.4064/ap-6-1-99-104},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-6-1-99-104/}
}