Jason Scott-Warren’s original blog post:
https://www.english.cam.ac.uk/cmt/?p=5751
I’m going to claim to have identified John Milton’s copy of the Shakespeare First Folio of 1623.
There is also a Guardian article with more art and less matter: https://www.theguardian.com/books/2019/sep/16/when-milton-met-shakespeare-poets-notes-on-bard-appear-to-have-been-found