@article{M2AN_1986__20_3_427_0,
     author = {Crouzeix, Michel},
     title = {A note on the complex and real operator norms of real matrices},
     journal = {ESAIM: Mod\'elisation math\'ematique et analyse num\'erique},
     pages = {427--428},
     publisher = {AFCET - Gauthier-Villars},
     address = {Paris},
     volume = {20},
     number = {3},
     year = {1986},
     mrnumber = {862785},
     zbl = {0609.15013},
     language = {en},
     url = {http://www.numdam.org/item/M2AN_1986__20_3_427_0/}
}