@article{Matkowski:2009,
author
=
"J.Matkowski and J.Rätz",
title
=
"Equality in Minkowski inequality and a characterization of L-norm",
journal
=
"Demonstratio Mathematica",
volume
=
"Vol. 30",
number
=
"no 1",
pages
=
"53--62",
year
=
"1997",
}