1. Indian Polity By M. Laxmikanth:
This book has been specifically designed to meet the academic needs of the civil services’ aspirants and essential for prelims and mains. It is very important resource, to understand features of the political system in the country as well as the trends. It is written in easy and clear language, and covers everything about Indian politics including articles of the constitution, constitutional amendments, ministries and departments of the central government.
2. Our Parliament By Subhash C. Kashyap:
Our Parliament is a book written by India’s former Secretary General Subhash C. Kashyap. This book explains the different facets and history of evolution of Indian parliament to its present form, its hierarchy, functions, responsibilities and other factors, in a lucid manner.
3. NCERT books:
NCERT books are very important books as these books contain all basic concepts required for developing basic understanding for UPSC. These are in very easy and interesting language, so number of books doesn’t matter. Also go through How to read NCERT books.