● Book in preparation: Analysis and Geometry of Sub-Riemannian Spaces, With Applications to Pde's, Birkhäuser.

Papers:

●  (with E. Sartori), Symmetry in exterior boundary value problems for quasilinear elliptic equations via blow-up and a priori estimates,

Advances in Differential Equations, (2) 4 (1999), 137-161.

● (with E. Sartori), Symmetry in a free boundary problem for degenerate parabolic equations on unbounded domains, Proc. Amer. Math. Soc. 129 (2001), no. 12, 3603-3610.

● (with D. Vassilev) Regularity near the characteristic set in the non-linear Dirichlet problem and conformal geometry of sub-Laplacians on Carnot groups, Math. Ann. 318 (2000), no. 3, 453-516

● (with D. Vassilev) Symmetry properties of positive entire solutions of Yamabe type equations on groups of Heisenberg type, Duke Math. J. 106 (2001), no. 3, 411-448.

●  (with L.Capogna and D. M. Nhieu)  Properties of harmonic measures in the Dirichlet problem for nilpotent Lie groups of Heisenberg type,  Amer. J. Math. 124 (2002), no. 2, 273-306

● (with D. Danielli) Properties of entire solutions of non-uniformly elliptic equations arising in geometry and in phase transition, Calc. Var. Partial Differential Equations 15 (2002), no. 4, 451-491.

● (with D. Danielli and S. Salsa) Variational inequalities with lack of ellipticity. Part I: interior regularity and non-degeneracy of the free boundary, Indiana Univ. Math. J. 52 (2003), no. 2, 361-398

● (with L. Capogna) Regularity of minimizers of the calculus of variations in Carnot groups via hypoellipticity of systems of Hörmander type,  J. Eur. Math. Soc. (JEMS) 5 (2003), no. 1, 1-40.

● (with D. Danielli and D. M. Nhieu) Notions of convexity in Carnot groups, Comm. Anal. Geom. 11 (2003), no. 2, 263-341

● (with D. Danielli and D. M. Nhieu) On the best possible character of the $L^Q$ norm in some a priori estimates for non-divergence form equations in Carnot groups, Proc. Amer. Math. Soc. 131 (2003), no. 11, 3487-3498

●(with D. Danielli, D.M. Nhieu and F. Tournier) The theorem of Busemann-Feller-Alexandrov in Carnot groups, Comm. Anal. Geom. 12 (2004), no. 4, 853-886.

● (with D. Danielli and D. M. Nhieu) Non-doubling Ahlfors measures, Perimeter measures, and the characterization of the trace space of Sobolev functions in Carnot-Carathéodory spaces, Memoirs of the Amer. Math. Soc., July 2006, vol. 182, no. 857, pp.119

● (with F. Tournier) New properties of convex functions in the Heisenberg group, Trans. Amer. Math. Soc., 358, no.5, 2011-2055

● (with D. Vassilev) Strong unique continuation properties of generalized Baouendi-Grushin operator, Comm. in Part. Diff. Equations, to appear

● (with L. Capogna)  Ahlfors regularity of the perimeter measure for minimally smooth hypersurfaces in Carnot-Carathéodory spaces, J. Geometric Analysis, to appear

● (with S. Pauls)  The Bernstein problem in the Heisenberg group, preprint

● (with D. Danielli and A. Petrosyan) The sub-elliptic obstacle problem:\\$C^{1,\alpha}$ regularity of
the free boundary, Advances in Math., to appear

● (with D. Danielli and D. M. Nhieu)  Sub-Riemannian calculus on hypersurfaces in Carnot groups, submitted paper

● (with D. Danielli and D. M. Nhieu), A partial solution of the isoperimetric problem in the Heisenberg group, Forum Mathematicum, to appear

● (with L. Capogna and S.Pauls)  Asymptotic behavior of the Gauss map near weakly singular characteristic points, work in progress.

● (with L. Capogna and D. M. Nhieu)  Properties of sub-elliptic harmonic measures: general Hörmander type operators, a preprint will be available shortly.

● (with D. Danielli and J. Spruck) The method of moving spheres for elliptic Weingarten surfaces, in preparation.

● (with D. Danielli)  Green functions in sub-Riemannian nonlinear potential theory, and the geometry of their level sets, a preprint will be available shortly.

● (with D. Danielli)  Inequalities of Hardy-Sobolev type in Carnot-Carath\'eodory
spaces, a preprint will be available shortly.

● (with E. Sartori) Symmetry for parabolic equations on time varying domains, in preparation.

● (with D.Danielli and D.M.Nhieu) A notable family of entire intrinsic minimal graphs in the Heisenberg group which are not
perimeter minimizing,  Amer. Journal Math., to appear

● (with D.Danielli, D.M.Nhieu and S. Pauls) A positive answer to the Bernstein problem in the
Heisenberg group H^1, submitted paper