Some popular textbooks on differential geometry include:
The book is suitable for:
If you require a free resource for self-study, several high-quality, legally free textbooks are available online (often under Creative Commons licenses or via university repositories): differential geometry by mittal and agarwal pdf free link
The book is packed with worked-out examples. For students preparing for exams (like UPSC or CSIR-NET), these step-by-step solutions are incredibly helpful for understanding how to apply the theory. Some popular textbooks on differential geometry include: The