@article{PawelkeButzer1968,
  author    = {Pawelke, Siegfried and Butzer, Paul L.},
  title     = {Semi-groups and resolvent operators},
  series = {Archive for Rational Mechanics and Analysis},
  volume    = {30},
  journal   = {Archive for Rational Mechanics and Analysis},
  number    = {2},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {0003-9527},
  doi       = {10.1007/BF00250941},
  pages     = {127 -- 147},
  year      = {1968},
  language  = {en}
}