[Math] Exercise books on functional analysis

Question

I have known a lot of excellent textbooks on functional analysis:

• Functional Analysis (Walter Rudin)

• Functional Analysis, Sobolev Spaces and Partial Differential Equations (Haim Brezis)

+….

I could not find some good exercise books on functional analysis.

Please help me to find some good books on exercise of functional analysis.

Thank you for all helping and comments.

Answer 1

Try Exercises in Functional Analysis by Constantin Costara and Dumitru Popa.