@article{SM_1976_28_4_a3,
     author = {L. A. Kalyakin},
     title = {On approximate methods of solving nonlinear boundary value problems with a~small parameter},
     journal = {Sbornik. Mathematics},
     pages = {491--500},
     publisher = {mathdoc},
     volume = {28},
     number = {4},
     year = {1976},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1976_28_4_a3/}
}