@article{AA_1998_10_2_a2,
     author = {Yu. N. Bibikov},
     title = {Bifurcation of the generation of invariant tori with infinitesimal frequency},
     journal = {Algebra i analiz},
     pages = {81--92},
     publisher = {mathdoc},
     volume = {10},
     number = {2},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_1998_10_2_a2/}
}