C. Mantegazza, G. Mascellani, G. Uraltsev:
On the Distributional Hessian of the Distance Function
Pacific J. of Math. Vol. 270, p. 151-166, 2014

S. Borghini, G. Mascellani, L. Mazzieri:
Some Sphere Theorems in Linear Potential Theory
(preprint) 2017