I had better luck focusing on long ebooks on an old tablet, which are attainable sub 20 on ebay, with some screen tweaks over a monitor. There's also projector type devices like really old wall projectors or even microfilm machines and equipment you might be able to find at a library sale in a big city or at a thrift store (else it won't be worth the cost whatsoever). Could also try audio books or as old as this work is tapes/cassettes. That's some other options, some just struggle with screens in general doesn't matter the format.

I've found theory and theory auxiliary type books in general can be really pricey, one of those things that make you wonder all right.