To cite ETAS/sd.tar.gz in publications use:

Jalilian A (2019). “ETAS: An R Package for Fitting the Space-Time ETAS Model to Earthquake Data.” Journal of Statistical Software, Code Snippets, 88(1), 1–39. doi: 10.18637/jss.v088.c01.

Corresponding BibTeX entry:

  @Article{,
    title = {{ETAS}: An {R} Package for Fitting the Space-Time {ETAS}
      Model to Earthquake Data},
    author = {Abdollah Jalilian},
    journal = {Journal of Statistical Software, Code Snippets},
    year = {2019},
    volume = {88},
    number = {1},
    pages = {1--39},
    doi = {10.18637/jss.v088.c01},
  }