%0 Journal Article %A V. V. Arestov %A E. E. Berdysheva %T Turán's problem for positive definite functions with supports in a hexagon %J Trudy Instituta matematiki i mehaniki %D 2001 %P 21-29 %V 7 %N 1 %U http://geodesic.mathdoc.fr/item/TIMM_2001_7_1_a1/ %G ru %F TIMM_2001_7_1_a1