@article{AA_1992_4_3_a1,
     author = {R. F. Bikbaev and S. B. Kuksin},
     title = {A~periodic boundary value problem for the {sine-Gordon} equation, its small {Hamiltonian} perturbations, and {KAM-deformations} of finite-gap tori},
     journal = {Algebra i analiz},
     pages = {42--78},
     publisher = {mathdoc},
     volume = {4},
     number = {3},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_1992_4_3_a1/}
}