%0 Journal Article %A M. S. Verbitsky %T Action of the Lie algebra $SO(5)$ on the cohomology of a hyperk\"ahler manifold %J Funkcionalʹnyj analiz i ego priloženiâ %D 1990 %P 70-71 %V 24 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/FAA_1990_24_3_a11/ %G ru %F FAA_1990_24_3_a11