To cite hetGP in publications use:

Binois M, Gramacy RB (2021). “hetGP: Heteroskedastic Gaussian Process Modeling and Sequential Design in R.” Journal of Statistical Software, 98(13), 1–44. doi: 10.18637/jss.v098.i13.

Corresponding BibTeX entry:

  @Article{,
    title = {{hetGP}: Heteroskedastic {G}aussian Process Modeling and
      Sequential Design in {R}},
    author = {Micka\"el Binois and Robert B. Gramacy},
    journal = {Journal of Statistical Software},
    year = {2021},
    volume = {98},
    number = {13},
    pages = {1--44},
    doi = {10.18637/jss.v098.i13},
  }