@article{DAN_1970_194_3_a7,
     author = {\`E. Muhamadiev},
     title = {On the theory of periodic solutions of systems of ordinary differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {510--513},
     publisher = {mathdoc},
     volume = {194},
     number = {3},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1970_194_3_a7/}
}