Previous: Measure Theory:
Chapter 5 of Folland's Real Analysis and/or chapters 1-3 of
Conway's A Course in Functional Analysis are a good place to
start -- as are chapters 9 and 10 of Royden's Real Analysis and
chapters 0,1 and 3 of Robert J. Zimmer's Elements of Functional
For more adventure, chapters 4 and 5 of Rudin's Real & Complex
Analysis and chapters 1-3 of Pedersen's Analysis Now are
sophisticated, but excellent resources.