Since the start of this long search to acquire maturity on the mathematical realm, in my country you always heard legends and stories about the soviet science books, when you find yourself giving your first steps on mathematical analysis, this book is going to be a nice companion, first, you are going to realize that, yes, soviet Russian science have certain mystique on its own, but nevertheless it is not inaccessible nor more difficult. I have came across with the concept of asymptotic approximations thanks to this book, something that I never going to forget, Спасибо Mr. Demidovich!