To cite package ‘GAprediction’ in publications use:

  Bohlin J (2016). _GAprediction: Prediction of gestational age with
  Illumina HumanMethylation450 data_. R package version 1.31.0,
  <https://bioconductor.org/packages/GAprediction>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {GAprediction: Prediction of gestational age with Illumina HumanMethylation450
data},
    author = {Jon Bohlin},
    year = {2016},
    note = {R package version 1.31.0},
    url = {https://bioconductor.org/packages/GAprediction},
  }