%0 Journal Article %A Kutev, Nikolai %A Milousheva, Velichka %T Complete Integrability of a Nonlinear Elliptic System, Generating Bi-umbilical Foliated Semi-symmetric Hypersurfaces in R^4 %J Mathematics and Education in Mathematics %D 2010 %P 141-148 %V 39 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/MEM_2010_39_1_a11/ %G en %F MEM_2010_39_1_a11