Book

Book : Drupal Multimedia (Paperback)

Now Drupal book is available for multimedia Technology. The Book named "Drupal Multimedia" can be purchased online by amazon.com

Book : Drupal for Education and E-Learning (Paperback)

Book : Using Drupal | 1st Edition By O'Reilly

Books : Pro Drupal Development | By John K. VanDyk, Dries Buytaert

Tutorial : Understanding Drupal DVD On Sale Now

Book : Using Drupal (Paperback)

Using Drupal (Paperback)

Info : Drupal White papers , Cheatsheets and Free books

If you have started with drupal and want to expand your knowledge, you either need to sit and spend time on Drupal Handbooks or buy some Drupal books.
Here I am giving some good collection of PDFs available on the web, which can be used for beginner or intermidiate developers.

Books : New Drupal Book - Learning Drupal 6 Module Development

Developing new modules for Drupal 6? Porting older modules? Packt Publishing has just released a new book, Learning Drupal 6 Module Development, by Matt Butcher. This book is targeted toward PHP programmers interested in Drupal 6 module development....[..]

The book deals with numerous topics, and introduces the prominent Drupal APIs. Here are some of the major topics covered:

Book : Building Powerful and Robust Websites With Drupal 6 

Book : Learning Drupal 6 Module Development

A practical tutorial for creating your first Drupal 6 modules with PHP