Here are the list of some good e books if you want to purchase online. This books are really comprehensive and have significant in dept study materials which will help you to kick start your drupal 7 project and build professional websites in a minute.
Amazon.com have a great collection of drupal 7 e books. You can order them online or read offline. Just checkout the links for more.
http://www.amazon.in/Drupal-7-Bible-Ric-Shreves/dp/8126531436?tag=googinhydr18418-21
http://www.amazon.in/Drupal-Development-Example-Beginners-Guide/dp/1849516804?tag=googinhydr18418-21
http://www.amazon.com/The-Definitive-Guide-Drupal-7-ebook/dp/B005PYQGYU
http://www.amazon.com/Drupal-Module-Development-John-Wilkins-ebook/dp/B0057761UY
Go to amazon.com and there you will find more ebooks on latest drupal development techniques written by experts.
