@article{SM_1989_62_1_a14,
     author = {A. L. \v{S}taras},
     title = {The averaging method for weakly nonlinear operator equations},
     journal = {Sbornik. Mathematics},
     pages = {223--242},
     publisher = {mathdoc},
     volume = {62},
     number = {1},
     year = {1989},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1989_62_1_a14/}
}