@article{Ho2011,
author = {Ho, D.E. and Imai, K. and King, G. and Stuart, E.A.},
title= {MatchIt: Nonparametric Preprocessing for Parametric Causal Inference},
year = {2011},
journal = {Journal of Statistical Software},
volume = {42},
number = {8},
pages = {1--28},
}