... ISBN0821813781 ) , 114 , ISBN 0821813781 122 . 123 . Hamel , Georg : Eine Basis aller Zahlen und die unstetigen Lösungen der Funktionalgleichung f ( x + y ) = f ( x ) + ƒ ( y ) . Mathematische Annalen , 60 1905 , Nr . 3 , 459–462 ( URL ...

Concise introductory treatment consists of three chapters: The Geometry of Hilbert Space, The Algebra of Operators, and The Analysis of Spectral Measures. A background in measure theory is the sole prerequisite. 1957 edition.

The notion of a Hilbert space is a central idea in functional analysis and this text demonstrates its applications in numerous branches of pure and applied mathematics.