To cite nCov2019 in publications use:

Wu T, Hu E, Ge X, Yu G (2021). “nCov2019: an R package for studying the COVID-19 coronavirus pandemic.” PeerJ, 9, e11421. doi: 10.7717/peerj.11421.

Corresponding BibTeX entry:

  @Article{,
    title = {nCov2019: an R package for studying the COVID-19
      coronavirus pandemic.},
    author = {Tianzhi Wu and Erqiang Hu and Xijin Ge and Guangchuang
      Yu},
    year = {2021},
    journal = {PeerJ},
    volume = {9},
    pages = {e11421},
    doi = {10.7717/peerj.11421},
  }