To cite etasFLP in publications use:

  Marcello Chiodi, Giada Adelfio (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

A BibTeX entry for LaTeX users is

  @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},
  }

Giada Adelfio, Marcello Chiodi, (2020). Including covariates in a
space-time point process with application to seismicity. Statistical
Methods and Applications. doi:10.1007/s10260-020-00543-5

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Including covariates in a space-time point process with application to seismicity},
    author = {Giada Adelfio and Marcello Chiodi},
    journal = {Statistical Methods and Applications},
    year = {2020},
    doi = {10.1007/s10260-020-00543-5},
  }