From the reviews:

“The book under review is a problem book, consisting of 448 problems … . The final chapter contains extensive notes with comments on the problems, which throw some light to the background and give hints and references to the literature. … For an advanced graduate student, the book should serve as valuable supplement … as well as a starting point for independent research. Intricate research problems and up-to-date treatment make the text highly recommended reading even for experts in the field.” (Marjeta Kramar Fijavž, Zentralblatt MATH, Vol. 1235, 2012)

“Solving the problems in the book is a very interesting enterprise, but the most beneficial thing is that these problems lead to very enlightening discussions and research problems. … this is a very interesting book which can prove useful to graduate students and mathematicians … . the Notes and the extended list of References are great invitations for more study and research.” (Mihaela Poplicher, The Mathematical Association of America, April, 2012)