@article{AA_2005_17_6_a1,
     author = {M. V. Bondarko},
     title = {Isogeny classes of formal groups over complete discrete valuation fields with an arbitrary residue field},
     journal = {Algebra i analiz},
     pages = {105--124},
     publisher = {mathdoc},
     volume = {17},
     number = {6},
     year = {2005},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2005_17_6_a1/}
}