Just for the record, I wasn't saying that books weren't useful, or didn't have advantages over wiki pages, but that they are not a fully reliable source either, and in either instance, it is a good idea to read multiple sources and perspectives.

You don't necessarily know the bias of the person writing any book, and unless someone challenges the accuracy publicly, you may not hear about it. Also, an advantage of wiki pages is that they can be updated with new information as it becomes available, whereas a book cannot. So there are advantages and disadvantages to both, but I wouldn't rely on any one of them as being accurate without separate sources being compared.