@article{MM2_1992__76_1_155753,
     author = {Isidro Nieto},
     title = {The {Normalizer} of the level {(2,2)-Heisenberg} {Group.}},
     journal = {Manuscripta mathematica},
     pages = {257--268},
     publisher = {mathdoc},
     volume = {76},
     number = {1},
     year = {1992},
     zbl = {0778.20019},
     url = {http://geodesic.mathdoc.fr/item/MM2_1992__76_1_155753/}
}