I'm trying to reorganize my home. I have a lot of books that I have read and kept over the years. A large percentage of them are ones where I have since purchased the e-book or I know they are available in e-book format. For the ones that are in e-book format... should I donate or give these physical books away to make space? My concern is that the e-book format may become obsolete and then I would no longer have the books available. I could probably repurchase them in whatever format eventually replaces e-books but that's a ton of money to spend... and a lot of regret if I give away the physical copy that I have now. Advice and opinions are welcomed. Thanks.