To cite package ‘europop’ in publications use:

Lincoln M, De Vries J (2017). europop: Historical Populations of European Cities, 1500-1800. R package version 0.3.1, https://github.com/mdlincoln/europop.

Corresponding BibTeX entry:

  @Manual{,
    title = {europop: Historical Populations of European Cities,
      1500-1800},
    author = {Matthew Lincoln and Jan {De Vries}},
    year = {2017},
    note = {R package version 0.3.1},
    url = {https://github.com/mdlincoln/europop},
  }