@article{bates2015,
  title={Fitting Linear Mixed-Effects Models Using <b>lme4</b>},
  author={Douglas M. Bates and Martin Mächler and Benjamin M. Bolker and Steve Walker},
  year={2015},
  journal={Journal of Statistical Software},
  doi={10.18637/jss.v067.i01},
  url={https://doi.org/10.18637/jss.v067.i01}
}