Aleksandra Samuļenkova shared this list of ‘sources concerning diacritics and special characters of the Latin script’ which is just too good to be buried on Twitter.
It would be great if we could all add more tips in the comments!
• An essay by Victor Gaultney on Problems of diacritic design for Latin script text faces
• An article by David Březina On Diacritics
• A great book about Central European diacritics: The Insects Project