@book{28552,
	author = {Pólya, George},
	title = {Problems and theorems in analysis},
	publisher = {Springer},
	year = {1972-76.},
	series = {Die Grundlehren der mathematischen Wissenschaften in Einzeldarstellungen},
	address = {Berlin},
	note = {Vol. 2 translated by C. E. Billigheimer.}
}