Lefschetz, S. (1977). Differential equations: Geometric theory .-2nded. (2d ed.). Dover Publications.
Chicago Edition CitationLefschetz, Solomon. Differential Equations: Geometric Theory .-2nded. 2d ed. New York: Dover Publications, 1977.
Cita MLALefschetz, Solomon. Differential Equations: Geometric Theory .-2nded. 2d ed. Dover Publications, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.