@article{econhot_econhot-cited-e2b570fb23fd289c,
  title = {Estimation of Regression Coefficients When Some Regressors are not Always Observed},
  author = {James M. Robins and Andrea G. Rotnitzky and Lue Ping Zhao},
  journal = {Journal of the American Statistical Association},
  year = {1994},
  volume = {89},
  number = {427},
  pages = {846-866},
  doi = {10.1080/01621459.1994.10476818},
  url = {https://doi.org/10.1080/01621459.1994.10476818}
}