@inproceedings{www20-paywalls,
  title        = {Keeping Out the Masses: Understanding the Popularity and Implications of Internet Paywalls},
  author       = {Panagiotis Papadopoulos and Peter Snyder and Benjamin Livshits},
  year         = 2020,
  month        = may,
  booktitle    = {International World Wide Web Conference (WWW)},
}