General Second-Order Linear Partial Differential Equations with Two Independent Variables
2016 ◽
pp. 245-258
1980 ◽
Vol 29
(4)
◽
pp. 454-461
2002 ◽
pp. 213-224
1993 ◽
Vol 89
(1)
◽
pp. 1-61
◽
1891 ◽
Vol 10
◽
pp. 63-70
1870 ◽
Vol 40
(264)
◽
pp. 35-41
1999 ◽
Vol 44
(2)
◽
pp. 177-203
◽