This classic of mathematics offers advanced undergraduates, graduate students, and professionals a comprehensive exposition of unbounded linear operator theory.... » 

This classic of mathematics offers advanced undergraduates, graduate students, and professionals a comprehensive exposition of unbounded linear operator theory. Its self-contained, systematic treatment covers both theory and applications to differential equations. Expressed in simple notation and a readable style, it includes examples and motivations for certain definitions and proofs.Dover unabridged republication of the edition published by McGrawHill in 1966. «