Can someone suggest me a book for $L^{p}$ spaces.

Question

I am reading functional analysis. I understand all the definitions, theorems, etc. But I am facing a problem in $L^p$ spaces.I am facing problems in understanding the relations like $L^p\subset L^{q}$,$L^p+L^q$,$L^p\cap L^q$, etc. Also finding difficult to construct counterexamples.So if someone suggests to me some book to understand all this that will be a great help. Thanks