You can easily download book from Google Books Website.
Google Books Website is: http://books.google.com/
This is the best online book center.
Here have approx. 30 categories books list which have thousand books.
This books reading are very easy but download process are not easy.
This software download link is:
-At first goes to http://books.google.com/
-select your favorite books from here.
Copy book’s ID from address Bar.
-now open Google Book Downloader
-then go File menu
-click Add book
- paste code
-Now click Queue button
-then you sees a book list
-click right button
After download, click right button to save this book then read book.