Some chapters of the book are suitable for undergraduate and graduate students. It is a good book since it presents many examples and exercises of different levels. Occasionally, different proofs are given for the same theorem which is inspiring and nice for illuminating / presentation of various methods. This is very useful, especially for beginners. In addition, the style of writing is good and clear. Great effort is made to make the book suitable for convenient reading, the hundreds of figures presented in the book are very helpful as well. -- Zentralblatt MATH ""Zentralblatt MATH""