books.google.com - "This book is an excellent classroom text, since it is clearly written, contains numerous problems and exercises, and at the end of each chapter has a summary of the significant results of the chapter." Quarterly of Applied Mathematics. Fundamental introduction for beginning student of absolute differential...http://books.google.com/books/about/Tensor_Calculus.html?id=8vlGhlxqZjsC&q=angle&utm_source=gb-gplus-shareTensor Calculus