For General Studies, here find mentioned the books that I referred
History: NCERT(old syllabus books for XI and XII)
India’s Struggle for Independence by Bipin Chandra
Note: First complete the NCERT books. You can arrange the old books from some seniors as the old syllabus books are not available in the market.
Geography: NCERT (XI and XII books, new syllabus books are also good).
Geography through Maps by Anil Kesari.
I also referred Wizard’s Geography for GS only because I was not sure about Geography syllabus.
Note: Have an Atlas handy while studying Geography. And when I say handy means, refer it whenever you encounter some geographical feature, relief, place, pattern, etc.
Polity: Indian Constitution by Laxmikanth,
Introduction to the Constitution of India by DD Basu (only if you want to)
Economy: Read NCERT books specially India Economic Development
Science and Technology: Read NCERT books (I did this)
Or You can rely on TMH Guide or Spectrum Guide.
Misc: India Year Book.
Note: Also have the syllabus handy while studying so that you do not overburden yourself with useless information. Stick to the syllabus.