Matthias I believe you can. I don’t know if you ever tried adding notes on a pdf with the on-screen keyboard (or generically use an on-screen keyboard from a kindle)… it’s a terrible experience.
When you read a book, a scientific paper or a CV it’s very natural to underline passages and taking notes, scribbling ideas and so as you would on normal paper.
I do that for my job on a daily basis and usually I would print-out and waste paper.
Don’t let me started on the possibility to search on my notes afterwards.
