@Article{ Mag6, author = { Magnani, Valentino }, title = { Blow-up of regular submanifolds in Heisenberg groups and applications }, journal = { Cent. Eur. J. Math. }, year = { 2006 }, volume = { 4 }, number = { 1 }, pages = { 82-109 }, URL = { http://cvgmt.sns.it/paper/1730/ }, note = { cvgmt preprint} }