To cite a11ytables in publications use:

  Dray M (2021) a11ytables: Create Spreadsheet Publications Following
  GSS Best Practice, Crown Copyright (Cabinet Office),
  https://github.com/co-analysis/a11ytables

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {a11ytables: Create Spreadsheet Publications Following GSS Best Practice},
    author = {Matt Dray},
    year = {2021},
    organization = {Crown Copyright (Cabinet Office)},
    url = {https://github.com/co-analysis/a11ytables},
  }