TITLE: Recommending books for introductory differential geometry
QUESTION [19 upvotes]: I was wondering if anyone could recommend some books for studying topics such as abstract manifolds, differential forms on manifolds, integration of differential forms, Stokes' theorem, de Rham cohomology, Hodge star operator? Our text is A Comprehensive Introduction to Differential Geometry by Spivak, but I think this book is very difficult for a beginner to learn.
Thanks in advance.

REPLY [5 votes]: A fine old book which hasn't been mentioned, which treats the topics asked for and more, is Frank Warner's Foundations of Differentiable Manifolds and Lie Groups. Maybe harder than Spivak, but Warner does a lot in a snappy way in not too many pages.