@incollection{AST_1992__209__73_0,
     author = {Rapinchuk, A. S.},
     title = {Congruence subgroup problem for algebraic groups: old and new},
     booktitle = {Journ\'ees arithm\'etiques de Gen\`eve - 9-13 septembre 1991},
     editor = {Coray D. F. and P\'etermann Y.-F. S},
     series = {Ast\'erisque},
     pages = {73--84},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {209},
     year = {1992},
     language = {en},
     url = {http://archive.numdam.org/item/AST_1992__209__73_0/}
}