Owl Tarot
It's not ideal, but I reckon people who don't have actual printed versions will be able to manage.
It's nice to know that real books still have some advantages.
I personally love having both a printed and an electronical version, but when I take books for more serious studies and meditations I prefer to do it with a book, take foot notes with a pencil, move around with it easier, turning pages etc.
Just posting this here as an introduction to the Aethyrs posted by Aeon in another thread, but which I think will be pretty useful to understand where Crowley was getting at with the Aethyrs and provides pretty helpful background information:
http://hermetic.com/crowley/confessions/chapter66.html
You could put a link for it in the OP as well Grigori, it is a nice place to start I think.