@article{DAN_1973_209_3_a6,
     author = {L. M. Lerman and L. P. Shilnikov},
     title = {On the classification of structurally stable nonautonomous systems of second order with a finite number of cells},
     journal = {Doklady Akademii Nauk},
     pages = {544--547},
     publisher = {mathdoc},
     volume = {209},
     number = {3},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_209_3_a6/}
}