@article{RM_2004_59_6_a2,
     author = {B. Balser},
     title = {Birkhoff's reduction problem},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {1047--1059},
     publisher = {mathdoc},
     volume = {59},
     number = {6},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_2004_59_6_a2/}
}