@article{10_4064_ap_6_1_51_68,
     author = {Z. Miko{\l}ajska},
     title = {Sur l'existence de solutions p\'eriodiques de l'\'equation diff\'erentielle du second ordre d\'ependant d'un param\`etre},
     journal = {Annales Polonici Mathematici},
     pages = {51--68},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {1959},
     doi = {10.4064/ap-6-1-51-68},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-6-1-51-68/}
}