Nonlinear Analysis: Theory, Methods & Applications
Nonlinear Analysis > 2004 > 56 > 4 > 465-484
Nonlinear Analysis > 2005 > 63 > 5-7 > e909-e918
Nonlinear Analysis > 2005 > 63 > 5-7 > e155-e164
Nonlinear Analysis > 2005 > 63 > 5-7 > e669-e677