I have a Kobo e-ink reader. The small 6-inch screen has a 300 PPI (Pixels Per Inch) resolution and does not fatigue the eyes for extended reading sessions. The

I have a Kobo e-ink reader. The small 6-inch screen has a 300 PPI (Pixels Per Inch) resolution and does not fatigue the eyes for extended reading sessions. The e-ink screen easily beats a LCD high-resolution or retina display for reading books. However, e-ink readers are only suitable for paperback-sized fiction or non-fiction titles. Everything else simply isn't suitable for the small 6-inch e-ink screen. PDFs at A4 (or US Letter size) are not suitable, as is any title with a lots of graphics or a complex page layout. Most academic or research papers are still in PDF and are rarely converted to ePub format suitable for reading on a e-Reader. Note: When I say paperback-sized, I'm referring books in the approx. 6-inch (15cm) size ballpark. Anything above A5 size is likely unsuitable for small e-Reader screens unless the book is text-only (or predominately text). Finally, if you are think of buying an Amazon Kindle 6-inch e-Reader, be aware that a lot of print books with graphics, charts, tables etc. have been poorly-converted to e-books and are unsuitable for small e-ink screens. Despite this, Amazon continues to misleadingly promote these titles as suitable for Kindle e-Readers when they are not.