To cite lubridate in publications use:

Yuancheng Xu, Athanasse Zafirov, Dan Kojis, Min Tan, Christina Ramirez (2020). FREEtree: A Tree-based Approach for High Dimensional Longitudinal Data With Correlated Features. WP

Corresponding BibTeX entry:

  @Article{,
    title = {FREEtree: A Tree-based Approach for High Dimensional
      Longitudinal Data With Correlated Features},
    author = {Yuancheng Xu and Athanasse Zafirov and Christina Ramirez
      and Dan Kojis and Min Tan},
    journal = {Working Paper},
    year = {2020},
  }