@article{econhot_econhot-reading-26,
  title = {Sample Selection Bias as a Specification Error},
  author = {James J. Heckman},
  journal = {Econometrica},
  year = {1979},
  volume = {47},
  number = {1},
  pages = {153},
  doi = {10.2307/1912352},
  url = {https://doi.org/10.2307/1912352}
}