See : BOOKS FOR PRELIMS
To gain knowledge on diverse topics it is prudent to read standard texts rather than depending on materials provided by various coaching institutions. First hand reading of basic books enables aspirant to tackle questions of different dimensions.
Reading newspaper everyday is sine qua non of UPSC preparation. A fortnightly magazine like Frontline is a must to enhance understanding about current events related to India and abroad. If possible, also go through The Economist magazine to understand international events.
Following is the list of books that are necessary for UPSC Civil Services Mains exam.
4) India Since Independence – new edition (Bipan Chandra)
Available on Amazon India
Or Buy this Imported Vesrion updated with in-depth chapters on Arab Spring and 2008 Financial Crisis: Mastering Modern World History -5th Edition, Norman Lowe
Or this book from Government of India: The Gazetteer of India: History and Culture Vol II
17) History of the World from the Late Nineteenth to the Early Twenty First Century – Arjun Dev (As Norman Lowe is not available anywhere, This is the best book available that covers all the topics)
Other Books Civil Services Aspirants Must Read (DURING LEISURE):
Of course you need to read NCERT texts as well. The above list is for reference and reading as well. As you have plenty of time for Mains, you can savour these books leisurely.
Don’t forget: The Hindu is the mother of Mains preparation now. Cut and Paste every article related to syllabus from October 2012 to November 2013!