共 15 条
[11]
KASHAMA MN, 1996, J DIFFER EQUATIONS, V132, P46
[13]
LANDESMAN EM, 1970, J MATH MECH, V19, P609
[14]
Li S., 1997, TOPOL METHOD NONL AN, V10, P123
[15]
Mawhin J., 1989, CRITICAL POINT THEOR