It falls because people sell
It's most likely falling because it reached a round number (5000) and many people use round numbers to cash out. Besides, after the recent rise, a correction was due... So everything is following its "natural" course. I don't really think the ICO situation played a role.
I don't think there are books on the subject.
More importantly it is selling by few people and followed by masses or rather its the panic and fud which created people to sell. But then people buy a lot too and bitcoin reaches so high with days, so there is always a time when there is a little awkward news and sell panic will show up.
