@article{MAT_1962_6_5_a6,
     author = {Ph. Hartman},
     title = {On boundary value problems for systems of ordinary, nonlinear, second order differential equations},
     journal = {Matematika},
     pages = {69--86},
     publisher = {mathdoc},
     volume = {6},
     number = {5},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MAT_1962_6_5_a6/}
}