Classification of Second-Order Linear Equations
1969 ◽
Vol 3
(4)
◽
pp. 594-623
◽
Keyword(s):
1974 ◽
Vol 15
(12)
◽
pp. 2063-2066
◽
Keyword(s):
1976 ◽
Vol 56
(2)
◽
pp. 452-459
◽