Differential equations :
Lefschetz, Solomon.
Differential equations : geometric theory / by Solomon Lefschetz. - 2nd ed. - New York, N.Y. : Dover Publications, 1977. - x, 390 p.
0486634639
Differential equations.
Differential equations : geometric theory / by Solomon Lefschetz. - 2nd ed. - New York, N.Y. : Dover Publications, 1977. - x, 390 p.
0486634639
Differential equations.