TY  - JOUR
AU  - I. G. Shcherbak
TI  - Focal set of a surface with boundary, and caustics of groups generated by reflections $B_k$, $C_k$, and $F_4$
JO  - Funkcionalʹnyj analiz i ego priloženiâ
PY  - 1984
SP  - 90
EP  - 91
VL  - 18
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/FAA_1984_18_1_a23/
LA  - ru
ID  - FAA_1984_18_1_a23
ER  -