Such an all-encompassing answer, I hesitate to add anything, but just to say, (in support I hasten to mention) that my PRS 650 can use cards etc.. so you could, with the hugely burdensome task of keeping enough of them to fill a (small) matchbox, practically have the entire British Library with you for innstance access - should you ever fill up the HD .
[Or whatever my reader uses - it's all magic to me, like aeroplanes to be totally honest !]
