To cite standardize in publications use:

Eager C (2017). standardize: Tools for Standardizing Variables for Regression in R. R package version 0.2.1, https://CRAN.R-project.org/package=standardize.

Corresponding BibTeX entry:

  @Manual{,
    title = {standardize: Tools for Standardizing Variables for
      Regression in R},
    author = {Christopher D Eager},
    year = {2017},
    note = {R package version 0.2.1},
    url = {https://CRAN.R-project.org/package=standardize},
  }