@article{SF_1981__23_134527,
     author = {K.H. Hofmann and J.D. Lawson},
     title = {The local theory of semigroups in nilpotent {Lie} groups.},
     journal = {Semigroup forum},
     pages = {343--358},
     year = {1981},
     volume = {23},
     zbl = {0531.22002},
     url = {http://geodesic.mathdoc.fr/item/SF_1981__23_134527/}
}