To cite package 'ipdw' in publications use:

  Jemma Stachelek (). ipdw: spatial interpolation by Inverse Path
  Distance Weighting. R package version 2.0-0.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {ipdw: spatial interpolation by Inverse Path Distance Weighting.},
    author = {Jemma Stachelek},
    note = {R package version 2.0-0},
    url = {https://cran.r-project.org/package=ipdw},
  }