@article{FAA_1984_18_1_a23,
     author = {I. G. Shcherbak},
     title = {Focal set of a surface with boundary, and caustics of groups generated by reflections $B_k$, $C_k$, and $F_4$},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {90--91},
     publisher = {mathdoc},
     volume = {18},
     number = {1},
     year = {1984},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1984_18_1_a23/}
}