To cite package ‘tls’ in publications use:

  Li Y, Chen K, Yan J (2018). _tls: Tools of Total Least Squares in
  Error-in-variables Models_. R package version 0.1.0,
  <https://github.com/liyanstat/tls>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {tls: Tools of Total Least Squares in Error-in-variables Models},
    author = {Yan Li and Kun Chen and Jun Yan},
    year = {2018},
    note = {R package version 0.1.0},
    url = {https://github.com/liyanstat/tls},
  }