%0 Journal Article %A A. B. Grigorian %T Algebraic multigrid preconditioner for elliptic problems with mixed type boundary conditions. I. Two-grid preconditioners %J Proceedings of the Yerevan State University. Physical and mathematical sciences %D 2006 %P 37-48 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/UZERU_2006_1_a3/ %G ru %F UZERU_2006_1_a3