I'm looking for a reference of a result in Optimal Transport. I know that if $\Omega$ is a compact subset of $\mathbb R^n$ and $c\in C^1$ (the transportation cost), then $c$ is Lipschitz continuous on $\Omega\times\Omega$ and hence all the Kantorovich potentials, which are $c$-concave, are Lipschitz as well, and then differentiable a.e. May you suggest me a reference (book/article) for such a (combination of) result(s)?
Thank you
The result is given in "Lectures on Optimal Transport" by Ambrosio, Brué and Semola.