  I wrote this book in a "do-it-yourself" style so that I give only a draft of
tensor theory, which includes formulating definitions and theorems and giving
basic ideas and formulas. All other work such as proving consistence of
definitions, deriving formulas, proving theorems or completing details to
proofs is left to the reader in the form of numerous exercises. I hope that
this style makes learning the subject really quick and more effective for
understanding and memorizing.
