@article{TM_1949_28_a6,
     author = {L. V. Kantorovich},
     title = {On differential equations of the form $x''=f(x)$},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {148--151},
     publisher = {mathdoc},
     volume = {28},
     year = {1949},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1949_28_a6/}
}