Some of my friends and me want to study the subject of Riemannian manifolds, and we are looking for an introductory text to study that subject. We studied differential geometry, and are about to finish out B.A. this year.
We consider studying afterwards about covering spaces of Riemannian manifolds.
Do you have any recommandations for such a text, that would be comfortable to study from and that will deal also with more advanced material on that subject?
Thanks in advance.