CALCULUS OF VARIATIONS AND PARTIAL DIFFERENTIAL EQUATIONS, vol. 34, no. 3, page. 321 - 339, 2009-03
JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, vol. 382, no. 1, page. 162 - 171, 2011-10-01
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS, vol. 23, no. 4, page. 1277 - 1294, 2009-04