Here are some interesting papers and resources on the Indian economy by Nitin Singhania:
Master Indian Economy with Nitin Singhania: Your Guide to Free Resources For UPSC aspirants and students of economics, Nitin Singhania’s Indian Economy
While a complete, official "free" version of Nitin Singhania Indian Economy
Since the official textbook is not free, you can use these authorized or open-access materials to build your paper: : Comprehensive playlists, such as the Complete Indian Economy by Nanki Baweja , follow the Nitin Singhania curriculum in detail.