On the periodic boundary-value problem for systems of second-order nonlinear ordinary differential equations
1995 ◽
Vol 18
(4)
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pp. 757-764
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2010 ◽
Vol 129
(1-2)
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pp. 166-181
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2007 ◽
Vol 193
(2)
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pp. 560-571
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2004 ◽
Vol 155
(3)
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pp. 709-726
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