@article{UFA_2014_6_1_a7,
     author = {E. M. Mukhamsdiev and I. D. Nurov and M. Sh. Khalilova},
     title = {Limiting cycles of piece-linear second order differential equations},
     journal = {Ufa mathematical journal},
     pages = {80--89},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {2014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/UFA_2014_6_1_a7/}
}