@article {1994,
	title = {A version of Olech\\\'s lemma in a problem of the calculus of variations},
	journal = {SIAM J. Control Optim. 32 (1994) 1114-1127},
	year = {1994},
	publisher = {SIAM},
	abstract = {This paper studies the solutions of the minimum problem for a functional of the gradient under linear boundary conditions. A necessary and sufficient condition, based on the facial structure of the epigraph of the integrand, is provided for the continuous dependence of the solutions on boundary data.},
	doi = {10.1137/S0363012992234669},
	url = {http://hdl.handle.net/1963/3514},
	author = {Arrigo Cellina and Sandro Zagatti}
}
