To cite penfa in publications use:

Elena G, Giampiero M, Irini M (2021). “Single- and Multiple-Group Penalized Factor Analysis: A Trust-Region Algorithm Approach with Integrated Automatic Multiple Tuning Parameter Selection.” Psychometrika, 86(1), 65-95. https://doi.org/10.1007/s11336-021-09751-8.

Geminiani E, Marra G, Moustaki I (2021). penfa: Single- And Multiple-Group Penalized Factor Analysis. R package version 0.1.1.

Corresponding BibTeX entries:

  @Article{,
    title = {Single- and Multiple-Group Penalized Factor Analysis: A
      Trust-Region Algorithm Approach with Integrated Automatic
      Multiple Tuning Parameter Selection},
    author = {Geminiani Elena and Marra Giampiero and Moustaki Irini},
    journal = {Psychometrika},
    year = {2021},
    volume = {86},
    number = {1},
    pages = {65-95},
    url = {https://doi.org/10.1007/s11336-021-09751-8},
  }

  @Manual{,
    title = {penfa: Single- And Multiple-Group Penalized Factor
      Analysis},
    author = {Elena Geminiani and Giampiero Marra and Irini Moustaki},
    year = {2021},
    note = {R package version 0.1.1},
  }