[1] AHLBRANDT C. D., HINTON D. B., LEWIS R. T.:
The effect of variable change on oscillation and disconjugacy criteria with application to spectral theory and asymptotic theory. J. Math. Anal. Appl. 81, 1981, 234-277.
MR 0618771
[2] ATKINSON F. V., KAPER H. G., KWONG M. K.:
An oscillation criterion for second order differential systems. Proc. Amer. Math. Soc. 96, 1985, 91-96.
MR 0781063
[3] BELLMAN R.: Vvedenie v teoriu matric. Nauka, Moskva 1976.
[4] BYRES R., HARRIS B. J., KWONG M. K.:
Weighted means and oscillation conditions for second order matriх differential equations. J. Diff. Equations 61, 1986, 164-177.
MR 0823400
[5] BORŮVKA O.:
Linear Differentialtransformationen 2. Ordnung. VEB Deutscher Verlag der Wissenschaften, Berlin 1967.
MR 0236448
[6] DOŠLÝ O.:
Riccati matrix differential equation and classification of disconjugate differential systems. Arch. Math. 23, 1987, 231-242.
MR 0930783
[7] HARTMAN P. :
Ordinary Differential Equations. John Wiley, New York, London, Sydney 1964.
MR 0171038 |
Zbl 0125.32102
[8] HARTMAN P.:
Oscillation criteria for self-adjoint second order differential systems and "principal sectional curvatures". J. Diff. Equations 34, 1979, 326-338.
MR 0550049 |
Zbl 0443.34029
[9] HINTON D. B., LEWIS R. T.:
Oscillation theory for generalized second order differential equations. Rocky Mountain J. Math. 10, 1980, 751-766.
MR 0595103 |
Zbl 0485.34021
[10] KAPER H. G., KWONG M. K.:
Oscillation of two-dimensional linear second-order differential systems. J. Diff. Equations 56, 1985, 195-205.
MR 0774162 |
Zbl 0571.34024
[11] KAPER H. G., KWONG M. K.:
Oscillation theory for linear second-order differential systems. Canadian Math. Soc. Conference Proceedings 8, 1987, 187-187.
MR 0909909 |
Zbl 0629.34040
[12] MORSE M.:
A generalization of the Sturm separation and comparison theorem in n-space. Math. Ann. 103, 1930, 52-69.
MR 1512617
[13] MÜLLER-PFEIFFER E.:
Existence of conjugate points for second and fourth order differential equations. Proc. Roy. Soc. Edinburgh 89A, 198 V 281-291.
MR 0635764
[14] MÜLLER-PFEIFFER R.:
An oscillation theorem for certain self-adjoint differential equations. Math. Nachr. 108, 1982. 79-92.
MR 0695118
[15] NOUSSIAR E. S., SWANSON C. A.:
Oscillation criteria for differential systems. J. Math. Anal. Appl. 36, 1971 575-580.
MR 0296417
[17] SCHMINKE V. W.:
The lower spectrum of Schrödinger operator. Arch. Rational Mech. Anal. 75, 1981, 147-155.
MR 0605526
[18] SWANSON C. A.:
Comparison and Oscillation Theory of Linear Differential Equations. Acad. Press, New York and London 1968.
MR 0463570 |
Zbl 0191.09904
[19] TIPLER F. J.:
General relativity and conjugate differential equations. J. Diff. Equations 30, 1978, 165-174.
MR 0513268