To cite the 'BIFIEsurvey' package in publications use:

BIFIE (2017). BIFIEsurvey: Tools for survey statistics in educational assessment. R package version 2.1-6. https://CRAN.R-project.org/package=BIFIEsurvey

Corresponding BibTeX entry:

  @Manual{,
    title = {BIFIEsurvey: Tools for survey statistics in educational
      assessment},
    author = {{BIFIE}},
    year = {2017},
    note = {R package version 2.1-6},
    url = {https://CRAN.R-project.org/package=BIFIEsurvey},
  }