To cite package ‘pgca’ in publications use:

  Takhar M, Sasaki M, Hollander Z, Kepplinger D, Smith D, McManus B,
  McMaster W, Ng R, Cohen Freue G (Under revision). “PGCA: An Algorithm
  to Link Protein Groups Created from MS/MS Data.” _PLOS ONE_. R
  package version 1.29.0.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {PGCA: An Algorithm to Link Protein Groups Created from MS/MS Data},
    author = {Mandeep Takhar and Mayu Sasaki and Zsuzsanna Hollander and David Kepplinger and Derek Smith and Bruce McManus and W. Robert McMaster and Raymond T. Ng and Gabriela V. {Cohen Freue}},
    journal = {PLOS ONE},
    year = {Under revision},
    note = {R package version 1.29.0},
  }