To cite package ‘face’ in publications use:

Li C, Xiao L, Checkley W, Crainiceanu C (2025). face: Fast Covariance Estimation for Sparse Functional Data. R package version 0.1-8, https://CRAN.R-project.org/package=face.

Corresponding BibTeX entry:

  @Manual{,
    title = {face: Fast Covariance Estimation for Sparse Functional
      Data},
    author = {Cai Li and Luo Xiao and William Checkley and Ciprian
      Crainiceanu},
    year = {2025},
    note = {R package version 0.1-8},
    url = {https://CRAN.R-project.org/package=face},
  }