@article{MAN_1989__285_1_164620,
     author = {Michael Shapiro},
     title = {A geometric approach to the almost convexity and growth of some nilpotent groups.},
     journal = {Mathematische Annalen},
     pages = {601--624},
     year = {1989},
     volume = {285},
     number = {1},
     zbl = {0693.20037},
     url = {http://geodesic.mathdoc.fr/item/MAN_1989__285_1_164620/}
}