@article{MOMA_1963__67_177200,
     author = {P. Waltman},
     title = {Some {Properties} of {Solutions} of u'' + a(t) f(u) = 0.},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {50--54},
     publisher = {mathdoc},
     volume = {67},
     year = {1963},
     zbl = {0116.29401},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1963__67_177200/}
}