%0 Journal Article %A I. P. Dzyub %A V. A. Nikolaev %T Method of variational derivatives in the theory of spin waves at low temperatures %J Teoretičeskaâ i matematičeskaâ fizika %D 1977 %P 237-246 %V 32 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/TMF_1977_32_2_a6/ %G ru %F TMF_1977_32_2_a6