If you cannot find the Nitin Singhania book even legally used, do not worry. The search intent truly means: "I want high-quality UPSC economy preparation at zero cost."
While the physical book is a paid McGraw Hill publication, several free resources can supplement your study: Nitin Singhania's Indian Economy Checklist | PDF - Scribd indian economy nitin singhania free
YouTube channel offers a 32-lesson, 36-hour playlist that follows Nitin Singhania's book systematically. Topic-wise Checklists If you cannot find the Nitin Singhania book