Google is the best search engine information in the world; however, sometimes you need another "little help" and is that often the tech giant does not give us the results we are looking for.
For example, when we want to find a book usually put the title of this and, usually, Google will always lead to pages where you can see the synopsis or opinions, but not the text itself.
To filter this literature search there is a small and simple trick that will undoubtedly facilitate the lives of thousands of people looking for books in PDF format to read.
The only thing you need to do when you're about to type on the search bar is write the book title and after that just write: "Filetype:PDF"
As an example, here you have: