ref-ggbiplot.r

#' @references
#'
#' Vincent Q. Vu (2014). ggbiplot: A 'ggplot2' based biplot. R package version
#' 0.55. <https://github.com/vqv/ggbiplot>, `experimental` branch
#'
#' Richard J Telford (2017). ggbiplot: A 'ggplot2' based biplot. R package
#' version 0.6. <https://github.com/richardjtelford/ggbiplot> (fork),
#' `experimental` branch
#'
#' Vilmantas Gegzna (2018). ggbiplot: A 'ggplot2' based biplot. R package
#' version 0.55. <https://github.com/forked-packages/ggbiplot> (fork), `experimental`
#' branch
#'