@article{CMUC_1978__19_4_a4,
     author = {Young, N. J.},
     title = {Norms of certain rational functions of a matrix and {Schur's} criterion for polynomials},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {673--688},
     publisher = {mathdoc},
     volume = {19},
     number = {4},
     year = {1978},
     mrnumber = {518179},
     zbl = {0388.30004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1978__19_4_a4/}
}