@article{ELA_2009__18__a56,
     author = {Drury, Stephen W.},
     title = {Operator norms of words formed from positive-definite matrices},
     journal = {The electronic journal of linear algebra},
     pages = {13--20},
     publisher = {mathdoc},
     volume = {18},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ELA_2009__18__a56/}
}