@article{Imai2010,
author = {Imai, K. and Keele, L. and Tingley, D. },
title= {A general approach to causal mediation analysis},
year = {2010},
doi = {10.1037/a0020761},
journal = {Psychological Methods },
volume = {15},
number = {4},
pages = {309--334},
}