@article{Angrist1996,
author = {Angrist, J. and Imbens, G.W. and Rubin, D.},
title= {Identification of causal effects using instrumental variables},
year = {1996},
doi = {10.1080/01621459.1996.10476902},
journal = {Journal of the American Statistical Association},
volume = {91},
number = {434},
pages = {444--472},
}