@article{VSGU_2009_2_a2,
     author = {A. A. Zhukova},
     title = {Rotation number like total characteristic of stability of {Hill} equation},
     journal = {Vestnik Samarskogo universiteta. Estestvennonau\v{c}na\^a seri\^a},
     pages = {26--32},
     publisher = {mathdoc},
     number = {2},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VSGU_2009_2_a2/}
}