@article{Matkowski:2012,
  author  = "J. Matkowski",
  title   = "Results of Tadeusz Świątkowski on algebraic sums of sets and their applications in the theory of subadditive functions",
  journal = "Journal of Applied Analysis",
  volume  = "Vol. 18",
  pages   = "97--116",
  year    = "2012",
}