For some people / families who are short on money or who live places where books might be hard to get access to - there is a free resource where you can download many books and texts, etc.
If you are able to pay, I recommend you buy from a bookstore like amazon, but if you can’t - then this might be a resource for you. Its also good just to give you the chance to review the book fully before you buy (I support intellectual property rights and think the authors need to make a living too).
You can search on title or topic and see what is of available. Just click on the book, then the “download” link (avoid the ads) and see what is helpful.
As an example, Here is a search on “schizophrenia” on the http://libgen.io website.
Information on the website: