@article{SF_1991__43_3_135109,
     author = {W.A.F. Ruppert},
     title = {Endomorphic actions of {{\ss}N} on the torus group.},
     journal = {Semigroup forum},
     pages = {202--217},
     publisher = {mathdoc},
     volume = {43},
     number = {3},
     year = {1991},
     zbl = {0739.22005},
     url = {http://geodesic.mathdoc.fr/item/SF_1991__43_3_135109/}
}