Ask HN: How to improve my Cython / Big Cython repos

I'm currently trying to be better at using Cython.

Since I know Python and C, I can already code in Cython, but cannot say I master it.

What are your recommendations (books, websites besides the official doc,…)?

Usually, reading some open source code helps, but I don't know big Cython projects with advanced Cython features (like classes, weakrefs, nogil, etc…), just Python projects that use a bit of Cython.