To cite CR2 in publications use:

Huang F, Li X (2022). “Using cluster robust standard errors when analyzing group randomized trials with few clusters.” Behavior Research Methods. https://link.springer.com/epdf/10.3758/s13428-021-01627-0?sharing_token=eIiUEDO3RA7xQuhBbPCeDZAH0g46feNdnc402WrhzypnhGrDXEDh-Uq8KAb789impq-2g25kEJJoCmKwEsXVbXuLkfLHza-JzNwtSCVJlJmHuydDfYKExT_sbRuNeHthDaXyIsjKk9tCd9jOuK4Px2WocvDFoVOyuV-5G7LSq_U%3D.

Huang F, Zhang B (????). CR2: Compute cluster robust standard errors with degrees of freedom adjustments. R package version 0.1.1, https://CRAN.R-project.org/package=CR2.

Corresponding BibTeX entries:

  @Article{,
    title = {Using cluster robust standard errors when analyzing group
      randomized trials with few clusters},
    author = {Francis Huang and Xintong Li},
    journal = {Behavior Research Methods},
    year = {2022},
    url =
      {https://link.springer.com/epdf/10.3758/s13428-021-01627-0?sharing_token=eIiUEDO3RA7xQuhBbPCeDZAH0g46feNdnc402WrhzypnhGrDXEDh-Uq8KAb789impq-2g25kEJJoCmKwEsXVbXuLkfLHza-JzNwtSCVJlJmHuydDfYKExT_sbRuNeHthDaXyIsjKk9tCd9jOuK4Px2WocvDFoVOyuV-5G7LSq_U%3D},
  }

  @Manual{,
    title = {CR2: Compute cluster robust standard errors with degrees
      of freedom adjustments},
    author = {Francis Huang and Bixi Zhang},
    note = {R package version 0.1.1},
    url = {https://CRAN.R-project.org/package=CR2},
  }