For those seeking an introductory book on differential geometry, several recommendations emerged, including "Modern Differential Geometry for Physicists" by Isham and "Introduction to Smooth Manifolds" by John M. Lee, which are noted for their comprehensive coverage. While Isham's book is valuable, it is more suited for understanding Yang-Mills theory rather than general relativity, as it focuses on Lie groups and fiber bundles. Erwin Kreyszig's "Introduction to Differential Geometry and Riemannian Geometry" was mentioned as a suitable alternative, though it may not be as widely recognized. Additionally, Manfredo Perdigão do Carmo's work received positive reviews, although some noted it might be outdated and overly reliant on local coordinates. Overall, Lee's text is frequently highlighted as a strong choice for those focused on the essentials of differential geometry relevant to general relativity.