@techreport{murrell-gggrid-2021,
  title="Accessing 'grid' from 'ggplot2'",
  author = {Paul Murrell},
  year={2021},
  note={version 1},
  institution={Department of Statistics, The University of Auckland},
  number={2021-01},
  url={https://stattech.blogs.auckland.ac.nz/2021/05/31/2021-01-accessing-grid-from-ggplot2/},
  doi={http://dx.doi.org/10.17608/k6.auckland.14703846}
}