In the link given below, You can download all those books:
Booklists
Booklists

Reference
History
- History: A Brief History of Modern India – Spectrum publications
- History: Indian Struggle for Independence – Bipin Chandra
Geography
- Geography: Certificate Physical and Human Geography – GOH Cheng Leong
Polity
- Polity: Indian Polity by Laxmikanth
- Polity: The Constitution of India by P.M. Bakshi
Economy
- Economy: Economy by Sankarganesh
- Economy: Indian Economy by Ramesh Singh (Reference only)