@misc{reciprocity-subsidiarity-and-solidarity,
  title   = {Social security solidarity models},
  author  = {Stüdli, Beat},
  year    = {2017},
  month   = {jun},
  url     = {https://www.historyofsocialsecurity.ch/articles/topics/core-concepts-and-terms/reciprocity-subsidiarity-and-solidarity}
}