@article{Matkowski:2005,
  author  = "J. Matkowski",
  title   = "Lagrangian mean-type mappings for which the arithmetic mean is invariant",
  journal = "Journal of Mathematical Analysis and Applications",
  volume  = "Vol. 309",
  number  = "no 1",
  pages   = "15--24",
  year    = "2005",
}