@article{10_4064_sm145_3_5,
     author = {Anders Olofsson},
     title = {An extremal problem in {Banach} algebras},
     journal = {Studia Mathematica},
     pages = {255--264},
     year = {2001},
     volume = {145},
     number = {3},
     doi = {10.4064/sm145-3-5},
     language = {de},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm145-3-5/}
}