@article{ZNSL_1992_202_a11,
     author = {M. N. Yakovlev},
     title = {Periodic solutions of second-order systems with one-sided restrictions to the growth of the right-hand side with respect to the first derivative},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {190--203},
     year = {1992},
     volume = {202},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1992_202_a11/}
}