Hybrids between hyperbolic and elliptic differential operators with constant coefficients
1966 ◽
Vol 72
(3)
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pp. 538-542
◽
1998 ◽
Vol 58
(2)
◽
pp. 213-221
◽
1994 ◽
Vol 74
(1)
◽
pp. 107-128
◽
1999 ◽
Vol 6
(2)
◽
pp. 207-225
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