An upper and lower solution approach for singular boundary value problems with sign changing non-linearities
2002 ◽
Vol 25
(6)
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pp. 491-506
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2002 ◽
Vol 50
(2)
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pp. 215-222
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1991 ◽
Vol 161
(1)
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pp. 78-116
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1996 ◽
Vol 32
(9)
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pp. 41-49
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2009 ◽
Vol 223
(2)
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pp. 543-551
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