@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 = {2018},
    url = {https://www.R-project.org/},
  }

  @Manual{pkg:magick,
    title = {magick: Advanced Graphics and Image-Processing in R},
    author = {Jeroen Ooms},
    year = {2019},
    note = {R package version 2.2},
    url = {https://CRAN.R-project.org/package=magick},
  }

  @Manual{pkg:gdiff,
    title = {gdiff: Graphical Difference Testing},
    author = {Paul Murrell},
    year = {2019},
    note = {R package version 0.1-0},
    url = {https://github.com/pmur002/},
  }

  @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: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{MetaPost,
title={METAPOST a user's manual},
author={John D. Hobby and {the MetaPost development team}},
year={2018},
url={http://www.tug.org/docs/metapost/mpman.pdf}
}

  @Article{pkg:graphicsQC,
    title = {Quality Control for Statistical Graphics: The {graphicsQC} Package for {R}},
    author = {Paul Murrell and Stephen Gardiner},
    journal = {Journal of Statistical Software},
    year = {2009},
    volume = {30},
    number = {1},
    pages = {1-28},
    url = {http://www.jstatsoft.org/v30/i01/},
  }

  @Manual{pkg:vdiffr,
    title = {vdiffr: Visual Regression Testing and Graphical Diffing},
    author = {Lionel Henry and Carl Sutherland and David Hong and T Jake Luciani and Matthieu Decorde and Vaudor Lise},
    year = {2019},
    note = {R package version 0.3.1},
    url = {https://CRAN.R-project.org/package=vdiffr},
  }

  @Manual{pkg:vtest,
    title = {vtest: Tools for visual testing of R packages},
    author = {Winston Chang},
    year = {2019},
    note = {R package version 0.0.3},
  }


  @Manual{pkg:Sxslt,
    title = {Sxslt: R interface to libxslt},
    author = {Duncan Temple Lang},
    year = {2019},
    note = {http://www.omegahat.org/Sxslt, http://www.omegahat.org},
  }

  @Article{pkg:testthat,
    author = {Hadley Wickham},
    title = {testthat: Get Started with Testing},
    journal = {The R Journal},
    year = {2011},
    volume = {3},
    pages = {5-10},
    url = {http://journal.r-project.org/archive/2011-1/RJournal_2011-1_Wickham.pdf},
  }

  @Manual{pkg:visualTest,
    title = {Perform Fuzzy Image Matching},
    author = {Chris Campbell and Gabor Csardi},
    year = {2019},
    note = {https://github.com/MangoTheCat/visualTest}
  }