Necessary conditions for the existence of a transformation operator for higher-order equations
1983 ◽
Vol 16
(3)
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pp. 219-221
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1984 ◽
Vol 22
(2)
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pp. 211-238
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1988 ◽
Vol 23
(1/2)
◽
pp. 9-40
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2012 ◽
Vol 390
(1)
◽
pp. 290-300
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