%0 Journal Article %A B. P. Kufarev %T Relations of the type “length and area principle” %J Doklady Akademii Nauk %D 1966 %P 268-270 %V 170 %N 2 %U http://geodesic.mathdoc.fr/item/DAN_1966_170_2_a8/ %G ru %F DAN_1966_170_2_a8