To cite the 'MFPCA' package in publications use:

Happ C (2020). MFPCA: Multivariate Functional Principal Component Analysis for Data Observed on Different Dimensional Domains. R package version 1.3-4, https://github.com/ClaraHapp/MFPCA.

Happ C, Greven S (2018). “Multivariate Functional Principal Component Analysis for Data Observed on Different (Dimensional) Domains.” Journal of the American Statistical Association, 113, 649-659. doi: 10.1080/01621459.2016.1273115.

Corresponding BibTeX entries:

  @Manual{,
    title = {MFPCA: Multivariate Functional Principal Component
      Analysis for Data Observed on Different Dimensional Domains},
    author = {Clara Happ},
    year = {2020},
    note = {R package version 1.3-4},
    url = {https://github.com/ClaraHapp/MFPCA},
  }
  @Article{,
    author = {Clara Happ and Sonja Greven},
    title = {Multivariate Functional Principal Component Analysis for
      Data Observed on Different (Dimensional) Domains},
    journal = {Journal of the American Statistical Association},
    year = {2018},
    volume = {113},
    issue = {522},
    pages = {649-659},
    doi = {10.1080/01621459.2016.1273115},
  }