@article{IM_1984__78_143166,
     author = {W. Singhof and Ch. Deninger},
     title = {The e-invariant and the spectrum of the {Lapacian} for compact nilmanifolds covered by {Heisenberg} groups.},
     journal = {Inventiones mathematicae},
     pages = {101--112},
     publisher = {mathdoc},
     volume = {78},
     year = {1984},
     zbl = {0558.55010},
     url = {http://geodesic.mathdoc.fr/item/IM_1984__78_143166/}
}