@article{10_4064_ap_6_1_87_91,
     author = {Z. Opial},
     title = {Sur une in\'egalit\'e de {C.} de la {Vall\'ee} {Poussin} dans la th\'eorie de l'\'equation diff\'erentielle lin\'eaire du second ordre},
     journal = {Annales Polonici Mathematici},
     pages = {87--91},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {1959},
     doi = {10.4064/ap-6-1-87-91},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-6-1-87-91/}
}