@article{PDM_2009_10_a33,
     author = {N. B. Butorina and S. A. Lykhina},
     title = {Representation of an arbitrary number with weight sum of essential subtrees},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {66--68},
     publisher = {mathdoc},
     number = {10},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2009_10_a33/}
}