@article{KohlerKreuterStuart2018,
  author    = {Ulrich Kohler and Frauke Kreuter and Elizabeth A. Stuart},
  title     = {Nonprobability Sampling and Causal Analysis},
  journal   = {Annual review of statistics and its application},
  volume    = {6},
  pages     = {149 -- 172},
  doi       = {10.1146/annurev-statistics-030718-104951},
  year      = {2018},
}