Nonlinear Analysis: Theory, Methods & Applications
Nonlinear Analysis > 2003 > 53 > 7-8 > 1017-1039
Nonlinear Analysis > 2005 > 61 > 4 > 543-549
Nonlinear Analysis > 2005 > 63 > 5-7 > e2247-e2256
Nonlinear Analysis > 2006 > 64 > 9 > 1984-1997