%0 Journal Article %A S. A. Stepin %T Asymptotic estimates for the kernel of the semigroup generated by a perturbation of the biharmonic operator by a potential %J Sbornik. Mathematics %D 2012 %P 893-921 %V 203 %N 6 %U http://geodesic.mathdoc.fr/item/SM_2012_203_6_a5/ %G en %F SM_2012_203_6_a5