Let $\Omega$ be a connected open set in $\Bbb R^n$. Suppose that I want theorems in multivariables calculus like divergence theorem or its relative like Green's identities or even Stoke's theorem to work, how wild can $\partial \Omega$ be?
Apparently piecewise smooth works, but I have seen weaker conditions as well. Does anyone have a good reference to books or papers that prove these result in a very general setting?