@article{MAN_1989__285_1_164596,
     author = {Peral Menal and Leonid N. Vaserstein},
     title = {On subgroups of {GL2} over non-commutative local rings which are normalized by elementary matrices.},
     journal = {Mathematische Annalen},
     pages = {221--232},
     publisher = {mathdoc},
     volume = {285},
     number = {1},
     year = {1989},
     zbl = {0662.20039},
     url = {http://geodesic.mathdoc.fr/item/MAN_1989__285_1_164596/}
}