To cite plotROC in publications use:

Sachs MC (2017). “plotROC: A Tool for Plotting ROC Curves.” Journal of Statistical Software, Code Snippets, 79(2), 1–19. doi:10.18637/jss.v079.c02.

Corresponding BibTeX entry:

  @Article{,
    title = {{plotROC}: A Tool for Plotting ROC Curves},
    author = {Michael C. Sachs},
    journal = {Journal of Statistical Software, Code Snippets},
    year = {2017},
    volume = {79},
    number = {2},
    pages = {1--19},
    doi = {10.18637/jss.v079.c02},
  }