To cite package ‘sonar’ in publications use:

  Gama J (2016). _sonar: Fundamental Formulas for Sonar_. R package
  version 1.0.2, <https://CRAN.R-project.org/package=sonar>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {sonar: Fundamental Formulas for Sonar},
    author = {Jose Gama},
    year = {2016},
    note = {R package version 1.0.2},
    url = {https://CRAN.R-project.org/package=sonar},
  }