%0 Journal Article
%A I. G. Shcherbak
%T Focal set of a surface with boundary, and caustics of groups generated by reflections $B_k$, $C_k$, and $F_4$
%J Funkcionalʹnyj analiz i ego priloženiâ
%D 1984
%P 90-91
%V 18
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/FAA_1984_18_1_a23/
%G ru
%F FAA_1984_18_1_a23