@article{10_4153_CMB_1980_072_5,
     author = {Felzenszwalb, Bernardo and Giambruno, Antonino},
     title = {Periodic and {Nil} {Polynomials} in {Rings}},
     journal = {Canadian mathematical bulletin},
     pages = {473--476},
     year = {1980},
     volume = {23},
     number = {4},
     doi = {10.4153/CMB-1980-072-5},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1980-072-5/}
}