%0 Journal Article %A Vladimir A. Koibaev %T On a question about generalized congruence subgroups %J Žurnal Sibirskogo federalʹnogo universiteta. Matematika i fizika %D 2018 %P 66-69 %V 11 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/JSFU_2018_11_1_a9/ %G en %F JSFU_2018_11_1_a9