A GENERALIZED UPPER AND LOWER SOLUTION METHOD FOR SINGULAR DISCRETE INITIAL VALUE PROBLEMS
2004 ◽
Vol 47
(4-5)
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pp. 739-750
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2009 ◽
Vol 223
(2)
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pp. 543-551
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2002 ◽
Vol 147
(1)
◽
pp. 41-52
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2011 ◽
Vol 285
◽
pp. 012016
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2014 ◽
Vol 51
(6)
◽
pp. 1123-1139
◽