@article{Rosenbaum1983,
author = {Rosenbaum, P. T. and Rubin, D. B.},
title= {The central role of propensity score in observational studies},
year = {1983},
doi = {10.1093/biomet/70.1.41},
journal = {Biometrika},
volume = {70},
pages = {41--55},
}