To cite messydates in publications use:

  J. Hollway. messydates: A broader date class for messy date
  information. 2021.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {messydates: A broader date class for messy date information},
    author = {James Hollway},
    year = {2021},
    version = {0.4.0},
    url = {https://github.com/globalgov/messydates},
  }