To cite package 'regress' in publications use:

Clifford D, McCullagh P (2020). The regress package. R package version 1.3-21.

Clifford D, McCullagh P (2006). “The regress function.” R News, 6(2), 6 10.

Corresponding BibTeX entries:

  @Manual{,
    title = {The regress package},
    author = {David Clifford and Peter McCullagh},
    year = {2020},
    note = {R package version 1.3-21},
  }
  @Article{,
    title = {The regress function},
    author = {David Clifford and Peter McCullagh},
    journal = {R News},
    year = {2006},
    volume = {6},
    number = {2},
    pages = {6},
    pages = {10},
    month = {May},
  }