  Let $n, m$ be positive integers, $n\geq m$. We make several remarks on the
relationship between approximate differentiability of higher order and
Morse-Sard properties. For instance, among other things we show that if a
function $f:\mathbb{R}^n\to\mathbb{R}^m$ is locally Lipschitz and is
approximately differentiable of order $i$ almost everywhere with respect to the
Hausdorff measure $\mathcal{H}^{i+m-2}$, for every $i=2, \dots, n-m+1$, then
$f$ has the Morse-Sard property (that is to say, the image of the critical set
of $f$ is null with respect to the Lebesgue measure in $\mathbb{R}^m$).
