M. Eminenti, C. Mantegazza:
Some Properties of the Distance Function and a Conjecture of De Giorgi
J. Geom. Anal. Vol. 14, N. 2, p. 267-279, 2004

M. Eminenti, G. La Nave, C. Mantegazza:
Ricci Solitons - The Equation Point of View
Manuscripta Math. Vol. 127, p. 345-367, 2008