G. Cupini, M. Guidorzi, E. Mascolo:
Regularity of minimizers of vectorial integrals with p-q growth
Nonlinear Anal. Vol. 54, N. 4, p. 591-616, 2003

P. Celada, G. Cupini, M. Guidorzi:
A sharp attainment result for nonconvex variational problems
Calc. Var. Vol. 20, p. 301-328, 2004

G. Cupini, M. Guidorzi, C. Marcelli:
Necessary conditions and non-existence results for autonomous nonconvex variational problems
J. Differential Equations Vol. 243, p. 329-348, 2007

P. Celada, G. Cupini, M. Guidorzi:
Existence and regularity of minimizers of nonconvex integrals with $p-q$ growth
ESAIM Control Optim. Calc. Var. Vol. 13, N. 2, p. 343-358, 2007

G. Cupini, M. Guidorzi, C. Marcelli:
Existence of minimizers of free autonomous variational problems via solvability of constrained ones.
Ann. Inst. H. Poincaré Anal. Non Linéaire Vol. 26, p. 1183-1205, 2009