TY - JOUR AU - I. S. Yurchenko TI - On the existence of continual closed $U$-set JO - Izvestiya of Saratov University. Mathematics. Mechanics. Informatics PY - 2016 SP - 76 EP - 79 VL - 16 IS - 1 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/ISU_2016_16_1_a6/ LA - ru ID - ISU_2016_16_1_a6 ER -