Pygal Citations

I use Pygal as a dependency for my scientific package. Is there a paper I can cite [similar to this page](https://www.scipy.org/citing.html)?

Start by reviewing the Pygal project context and the linked SciPy citing page to determine whether Pygal has a citable paper or other recommended reference. Done means documenting a confirmed citation recommendation or clearly explaining that none is available, in a location maintainers approve.

Written by the indexing model from the issue text.