@article{DAN_1960_131_6_a21,
     author = {M. M. Simkin},
     title = {Periodic modes in systems with nonlinear pulse elements},
     journal = {Doklady Akademii Nauk},
     pages = {1323--1326},
     publisher = {mathdoc},
     volume = {131},
     number = {6},
     year = {1960},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1960_131_6_a21/}
}