To cite etasFLP in publications use:

Chiodi M, Adelfio G (2017). “Mixed Non-Parametric and Parametric Estimation Techniques in R Package etasFLP for Earthquakes' Description.” Journal of Statistical Software, 76(3), 1–29. doi: 10.18637/jss.v076.i03.

Corresponding BibTeX entry:

  @Article{,
    title = {Mixed Non-Parametric and Parametric Estimation Techniques
      in {R} Package {etasFLP} for Earthquakes' Description},
    author = {Marcello Chiodi and Giada Adelfio},
    journal = {Journal of Statistical Software},
    year = {2017},
    volume = {76},
    number = {3},
    pages = {1--29},
    doi = {10.18637/jss.v076.i03},
  }