To cite echo.find in publications use:

Hannah De los Santos, Emily Collins, Kristin Bennett, Jennifer Hurley (2018). Finding Rhythms Using Extended Circadian Harmonic Oscillators (ECHO). R package version 2.0. URL https://CRAN.R-project.org/package=echo.find.

Corresponding BibTeX entry:

  @Manual{,
    title = {Finding Rhythms Using Extended Circadian Harmonic
      Oscillators (ECHO)},
    author = {Hannah De los Santos and Emily Collins and Kristin
      Bennett and Jennifer Hurley},
    journal = {Journal of Statistical Software},
    year = {2018},
    note = {R package version 2.0},
    url = {https://CRAN.R-project.org/package=echo.find},
  }