To cite package ‘a4Preproc’ in publications use:

  Talloen W, Verbeke T (2020). _a4Preproc: Automated Affymetrix Array
  Analysis Preprocessing Package_. R package version 1.53.0,
  <https://bioconductor.org/packages/a4Preproc>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {a4Preproc: Automated Affymetrix Array Analysis Preprocessing Package},
    author = {Willem Talloen and Tobias Verbeke},
    year = {2020},
    note = {R package version 1.53.0},
    url = {https://bioconductor.org/packages/a4Preproc},
  }