共 25 条
[1]
Ambrosetti A., 1972, ANN MAT PUR APPL, V93, P231, DOI DOI 10.1007/BF02412022
[6]
CODDINGTON E., 1955, Theory of ordinary differential equations
[8]
COSTA DG, 1991, 2 FRENCH CHIL S APPL, P165