@article{Huppler-Hullsiek2002,
author = {Huppler-Hullsiek, K. and Louis, T.A.},
title= {Propensity score modeling strategies for the causal analysis of observational data},
year = {2002},
doi = {10.1093/biostatistics/3.2.179},
volume = {3},
pages = {179--193},
}