@article{DE_1968_4_4_a1,
     author = {D. V. Izyumova and I. T. Kiguradze},
     title = {Some remarks on the solutions of the equation $u''+a(t)f(u)=0$},
     journal = {Differencialʹnye uravneni\^a},
     pages = {589--605},
     publisher = {mathdoc},
     volume = {4},
     number = {4},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1968_4_4_a1/}
}