To cite intsvy in publications use:

Caro DH, Biecek P (2017). “intsvy: An R Package for Analyzing International Large-Scale Assessment Data.” Journal of Statistical Software, 81(7), 1–44. doi:10.18637/jss.v081.i07.

Corresponding BibTeX entry:

  @Article{,
    title = {{intsvy}: An {R} Package for Analyzing International
      Large-Scale Assessment Data},
    author = {Daniel H. Caro and Przemys\l{}aw Biecek},
    journal = {Journal of Statistical Software},
    year = {2017},
    volume = {81},
    number = {7},
    pages = {1--44},
    doi = {10.18637/jss.v081.i07},
  }