[1] E. Barvínek:
Quadratic phases of differential equations y" + q(x) y = 0. Arch. Math. 8 (1972), 63-78.
MR 0326037
[2] J. H. Barrett:
A Prüfer transformation of matrix differential equations. Proc. Amer. Math. Soc. 8 (1957), 510-518.
MR 0087821
[3] O. Borůvka:
Lineare Differentialtransformationen 2. Ordnung. VEB Deutscher Verlag der Wissenschaften, Berlin 1967.
MR 0236448
[4] W. A. Coppel:
Disconjugacy. Lectures Notes in Mathematics 220, Springer Verlag, Berlin-New York-Heidelberg 1971.
MR 0460785 |
Zbl 0224.34003
[5] O. Došlý:
On transformation of self-adjoint linear differential systems and their reciprocals. to appear.
MR 2170475
[6] P. Hartman:
Self-adjoint, nonoscillatory systems of ordinary, second order, linear equations. Duke J. Math. 24 (1957), 25-35.
MR 0082591
[7] W. T. Reid:
A Prüfer transformation for matrix differential systems. Pacific J. Math. 8 (1958), 575-584.
MR 0099474
[8] W. T. Reid:
Sturmian Theory for Ordinary Differential Equations. John Wiley, New York 1980
MR 0606199 |
Zbl 0459.34001
[9] R. L. Sternberg:
Variational methods and non-oscillatory theorems for systems of differential equations. Duke J. Math. 19 (1952), 311-322.
MR 0048668