@article{MZM_1974_16_3_a7,
     author = {A. D. Bruno},
     title = {Normal form of differential equations with a~small parameter},
     journal = {Matemati\v{c}eskie zametki},
     pages = {407--414},
     publisher = {mathdoc},
     volume = {16},
     number = {3},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1974_16_3_a7/}
}