共 11 条
[3]
FONDA A, PERIODIC SOLUTIONS S
[4]
FONDA A, 1994, J COMP APPL MATH, V52
[5]
HABETS P, 1989, P AM MATH SOC, V109, P1035
[6]
Habets P., 1990, DIFFERENTIAL INTEGRA, V3, P1139
[7]
LAZER AC, 1987, P AM MATH SOC, V88, P109
[8]
Mawhin J., 1989, APPL MATH SCI, V74
[9]
RABINOWITZ P, 1968, CBMS, V65