[1] R. Bellman:
Stability Theory of Differential Equations. New York 1953 (Russian transl. I.I. L. Moscow 1954).
MR 0075365 |
Zbl 0053.24705
[2] O. Borůvka:
Linear Differential Transformation of the Second Order. The English Universities Pгess, London 1971.
MR 0463539
[3] F. Neuman:
Linear differential equations of the second order and their applications. Rend. Mat. 4 (1971), p. 559-617.
MR 0311972 |
Zbl 0227.34005