@article{preacher2004,
  title={SPSS and SAS procedures for estimating indirect effects in simple mediation models},
  author={Kristopher J. Preacher and Andrew F. Hayes},
  year={2004},
  journal={Behavior Research Methods, Instruments, & Computers},
  doi={10.3758/bf03206553},
  url={https://doi.org/10.3758/bf03206553}
}