@article{PFMT_2010_1_a3,
     author = {E. V. Varenikova},
     title = {Time symmetries of two dimensial nonautounomous differential systems},
     journal = {Problemy fiziki, matematiki i tehniki},
     pages = {22--24},
     publisher = {mathdoc},
     number = {1},
     year = {2010},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PFMT_2010_1_a3/}
}