I know Pohozaev-type identities are important tools for many PDEs including nonlinear, nonlocal problems, for showing nonexistence and uniqueness. However, is there any elementary reference on Pohozaev identity with applications? For example, I am interested in showing uniqueness of basic nonlinear PDE; model problem would be power type equation $$\begin{cases}(-\Delta) u=|u|^{p-1}u&\text{ in }\Omega\\ u=0&\text{ in }\Omega^c\end{cases}$$ via Pohozaev identity.
Thank you in advance.