Problems and Theorems in Analysis II by Polyà/Szegö is also available in the Classics in Mathematics series (3-540-63686-2).
Very few mathematical books are worth translating 50 years after their original publication. Polyá-Szegö is one! It was published in German by Springer in 1924, its English edition was widely acclaimed when it appeared from 1972 In the past more of the leading mathematicians proposed and solved problems than today Their collection of the best in analysis is a heritage of lasting value
George Polya
analysis analytic function convergence differential equation distribution integral integration logarithm maximum minimum theory of functions
From the reviews: "The present English edition is not a mere translation of the German original. Many new problems have been added. (Jahresb. DMV) "There are some excellent books which are indispensable to the instruction of indeed good mathematicians and this volume is, without any doubt, one of them. The broad horizon of the book, its clear style and logical construction are some of the qualities which assure
From the reviews: "The work is one of the real classics of this century; it has had much influence on teaching, on research in several branches of hard analysis, particularly complex function theory, and it has been an essential indispensable source book for those seriously interested in mathematical problems. These volumes contain many extraordinary problems and sequences of problems, mostly from some time past, well worth attention today and tomorrow. Written in the early twenties by two young mathematicians of outstanding talent, taste, breadth, perception, perseverence, and pedagogical skill, this work broke new ground in the teaching of mathematics and how to do mathematical research." -Bulletin of the American Mathematical Society