First Order Differential Equations. Exact Equations, Separation of Variables, Homogeneous and Linear Equations
1990 ◽
Vol 45
(11-12)
◽
pp. 1219-1229
◽
2018 ◽
Vol 38
(2)
◽
pp. 74-84
◽
1974 ◽
pp. 363-390