That's incredibly cool actually, what was the book? Could you share anything he wrote which you found especially interesting?
The book is "Making Good in Business" by Roger W. Babson. Babson gifted the book to Edison in 1921. Here is a link to a scan of another copy of the book in the Internet Archive: https://archive.org/details/bwb_P9-DAU-349/mode/2up
Here is my github repo with scans of the marginalia from Edison: https://github.com/RRWagner/Making-Good-in-Business-Babson-E...
The book is "Making Good in Business" by Roger W. Babson. Babson gifted the book to Edison in 1921. Here is a link to a scan of another copy of the book in the Internet Archive: https://archive.org/details/bwb_P9-DAU-349/mode/2up
Here is my github repo with scans of the marginalia from Edison: https://github.com/RRWagner/Making-Good-in-Business-Babson-E...