Optimal existence conditions for second order periodic solutions of delay differential equations with upper and lower solutions in the reverse order
2004 ◽
Vol 81
(6)
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pp. 707-717
2009 ◽
Vol 10
(5)
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pp. 3285-3297
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2010 ◽
Vol 9
(6)
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pp. 1529-1542
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2019 ◽
Vol 9
(3)
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pp. 298
2009 ◽
Vol 86
(7)
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pp. 1167-1181
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