@article{GDZPPN002337517,
title = {Quasiregular mappings of the Heisenberg group.},
journal = {Mathematische Annalen},
volume = {293},
year = {1992},
pages = {625-644},
zbl = {0754.30018},
url = {http://dml.mathdoc.fr/item/GDZPPN002337517}
}
Holopainen, Ilkka; Rickman, Seppo. Quasiregular mappings of the Heisenberg group.. Mathematische Annalen, Tome 293 (1992) pp. 625-644. http://gdmltest.u-ga.fr/item/GDZPPN002337517/