@article{Koh:01b,
  journal = {Numer. Funct. Anal. and Optimiz.},
  title = {{A} quantitative version of a theorem due to
           {B}orwein-{R}eich-{S}hafrir},
  pages = {641--656},
  year = 2001,
  volume = 22,
  author = {Kohlenbach, Ulrich},
}