To cite npphen in publications use:

Chávez RO, Estay SA, Lastra JA, Riquelme CG (2022). npphen: an R-package for Vegetation Phenological Cycle and Anomaly Detection using Remote Sensing Data..

Corresponding BibTeX entry:

  @Manual{,
    title = {{npphen}: an R-package for Vegetation Phenological Cycle
      and Anomaly Detection using Remote Sensing Data.},
    author = {Roberto O. Chávez and Sergio A. Estay and José A. Lastra
      and Carlos G. Riquelme},
    year = {2022},
  }