@article{SM_1995_186_7_a4,
     author = {L. A. Kalyakin},
     title = {On the problem of first correction in soliton perturbation theory},
     journal = {Sbornik. Mathematics},
     pages = {977--1002},
     publisher = {mathdoc},
     volume = {186},
     number = {7},
     year = {1995},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1995_186_7_a4/}
}