@article{SJIM_2010_13_2_a8,
     author = {N. A. Lyul'ko},
     title = {On the instability of hyperbolic systems on the plane under small periodic perturbation},
     journal = {Sibirskij \v{z}urnal industrialʹnoj matematiki},
     pages = {85--97},
     publisher = {mathdoc},
     volume = {13},
     number = {2},
     year = {2010},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/SJIM_2010_13_2_a8/}
}