Sometimes you need several books open (and pages marked) to figure something out. If you relied on e-Readers, you’d have to have as many e-Readers as you did books. My e-Reader also has a significantly smaller ‘page’ - and I’m not just talking the physical dimension, I’m referring to how many lines are displayed. Once again, this is a limiting factor.In my experience, technical books are not referred to in a serial fashion like you read a novel, it is more random, skipping back and forth from one book to another, from one page to another. e-Readers simply don’t work very well in that context.