%0 Journal Article
%A Bethuel, F.
%T A characterization of maps in $H^1 (B^3, S^2)$ which can be approximated by smooth maps
%J Annales de l'I.H.P. Analyse non linéaire
%D 1990
%P 269-286
%V 7
%N 4
%I Gauthier-Villars
%U http://www.numdam.org/item/AIHPC_1990__7_4_269_0/
%G en
%F AIHPC_1990__7_4_269_0