To cite package ‘restrend’ in publications use:

  Lorenz D (2017). _restrend: EStimate TRENDs_. R package version
  0.4.2, <https://github.com/usgs-r/restrend>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {restrend: EStimate TRENDs},
    author = {Dave Lorenz},
    year = {2017},
    note = {R package version 0.4.2},
    url = {https://github.com/usgs-r/restrend},
  }