To cite covatest in publications use:

Cappello C, De Iaco S, Posa D (2020). “covatest: An R Package for Selecting a Class of Space-Time Covariance Functions.” Journal of Statistical Software, 94(1), 1–42. doi:10.18637/jss.v094.i01.

Corresponding BibTeX entry:

  @Article{,
    title = {{covatest}: An {R} Package for Selecting a Class of
      Space-Time Covariance Functions},
    author = {Claudia Cappello and Sandra {De Iaco} and Donato Posa},
    journal = {Journal of Statistical Software},
    year = {2020},
    volume = {94},
    number = {1},
    pages = {1--42},
    doi = {10.18637/jss.v094.i01},
  }