“…The proof of Th. 2 mostly follows the steps of [9], the main improvement being the more precise Proposition 7. First of all by Kruzkov's doubling of variables, see [35], any entropy solution u to (1.1) satisfies in the sense of distributions that ∂ t |u(t, x) − u(t, y)| + div x (a(t, x) F (u(t, x), u(t, y)) + div y (a(t, y) F (u(t, x), u(t, y)) + G(u(t, x), u(t, y)) div x a(t, x) + G(u(t, y), u(t, x)) div y a(t, y) ≤ 0, Note that up to adding a constant in f , we may assume that f (0) = 0 thus normalizingḠ s.t.Ḡ(0, 0) = 0.…”