I wrote a 16-page article about the dark art of checksumming and it is still in kiosks in France ! Here is the link to the editor's site :
The article should become "free to read online" in mid-2023. It builds upon many of the subjects and data covered in this project and expands from there, I'd dare to say it's a "must read" if you're French and want to use/implement some checksum code. I'll see if I can make a short version in English somehow.