Existence and multiplicity results for systems of first order differential equations via the method of solution-regions
2019 ◽
Vol 8
(2S11)
◽
pp. 664-668
2018 ◽
Vol 38
(2)
◽
pp. 74-84
◽
1974 ◽
pp. 363-390
1991 ◽
Vol 155
(2)
◽
pp. 572-588
◽