@article {34438,
	title = {Comment on: {\textquoteright}Covariance Adjustment in Randomized Experiments and Observational Studies{\textquoteright}, by Paul Rosenbaum},
	journal = {Statistical Science},
	volume = {17},
	number = {3},
	year = {2002},
	pages = {304-307},
	author = {Guido Imbens and Joshua Angrist}
}
