@Manual{R,
    title = {R: A Language and Environment for Statistical Computing},
    author = {{R Core Team}},
    organization = {R Foundation for Statistical Computing},
    address = {Vienna, Austria},
    year = {2019},
    url = {https://www.R-project.org/},
  }

  @Manual{pkg:gridGraphics,
    title = {gridGraphics: Redraw Base Graphics Using 'grid' Graphics},
    author = {Paul Murrell and Zhijian Wen},
    year = {2020},
    note = {R package version 0.5-0},
    url = {https://CRAN.R-project.org/package=gridGraphics},
  }

  @Article{pkg:grImport,
    title = {Importing Vector Graphics: The {grImport} Package for {R}},
    author = {Paul Murrell},
    journal = {Journal of Statistical Software},
    year = {2009},
    volume = {30},
    number = {4},
    pages = {1--37},
    url = {http://www.jstatsoft.org/v30/i04/},
  }

  @Manual{pkg:grImport2,
    title = {grImport2: Importing 'SVG' Graphics},
    author = {Simon Potter and Paul Murrell},
    year = {2019},
    note = {R package version 0.2-0},
    url = {https://CRAN.R-project.org/package=grImport2},
  }

 @Manual{pkg:metapost,
    title = {metapost: Interface to 'MetaPost'},
    author = {Paul Murrell},
    year = {2019},
    note = {R package version 1.0-6},
    url = {https://CRAN.R-project.org/package=metapost},
  }

  @Manual{pkg:dvir,
    title = {dvir: Render DVI Files},
    author = {Paul Murrell},
    year = {2020},
    note = {R package version 0.2-0},
  }

  @Manual{pkg:layoutEngine,
    title = {layoutEngine: Render HTML},
    author = {Paul Murrell},
    year = {2020},
    note = {R package version 0.3-0},
  }

  @Manual{pkg:riverplot,
    title = {riverplot: Sankey or Ribbon Plots},
    author = {January Weiner},
    year = {2017},
    note = {R package version 0.6},
    url = {https://CRAN.R-project.org/package=riverplot},
  }

  @Manual{pkg:ggpattern,
    title = {ggpattern: Geoms with Patterns},
    author = {Mike FC},
    year = {2020},
    note = {http://github.com/coolbutuseless/ggpattern,
https://coolbutuseless.github.io/package/ggpattern/index.html},
  }

  @Book{pkg:ggplot2,
    author = {Hadley Wickham},
    title = {ggplot2: Elegant Graphics for Data Analysis},
    publisher = {Springer-Verlag New York},
    year = {2016},
    isbn = {978-3-319-24277-4},
    url = {https://ggplot2.tidyverse.org},
  }