To cite package ‘OPCreg’ in publications use:

  Guo G, Wei C (2025). _OPCreg: Online Principal Component Regression
  for Online Datasets_. R package version 3.0.0,
  <https://CRAN.R-project.org/package=OPCreg>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {OPCreg: Online Principal Component Regression for Online Datasets},
    author = {Guangbao Guo and Chunjie Wei},
    year = {2025},
    note = {R package version 3.0.0},
    url = {https://CRAN.R-project.org/package=OPCreg},
  }