@article{Higher-order-purity,
  title = "Ruling out higher-order interference from purity principles",
  author = "Howard Barnum and Ciarán Lee and Carlo Maria Scandolo and John Selby",
  year = "2017",
  journal = "Entropy",
  pages = "253",
  volume = "19",
  doi = "10.3390/e19060253",
}