[1] C. D. Ahlbrandt, D. B. Hinton and R. T. Lewis:
Necessary and sufficient conditions for the discreteness of the spectrum of certain singular differential operators. Canad. J. Math. 33 (1981), 229–246.
DOI 10.4153/CJM-1981-019-1 |
MR 0608867
[2] C. D. Ahlbrandt, D. B. Hinton and R. T. Lewis:
The effect of variable change on oscillation and disconjugacy criteria with applications to spectral theory and asymptotic theory. J. Math. Anal. Appl. 81 (1981), 234–277.
DOI 10.1016/0022-247X(81)90060-3 |
MR 0618771
[3] W. A. Coppel:
Disconjugacy. Lectures Notes in Mathematics, No. 220. Springer Verlag, Berlin-Heidelberg, 1971.
MR 0460785
[4] O. Došlý:
Oscillation criteria and the discreteness of the spectrum of self-adjoint, even order, differential operators. Proc. Roy. Soc. Edinburgh 119 A (1991), 219–232.
MR 1135970
[5] O. Došlý: Conditionally oscillatory equations and spectral properties of singular differential operators. In: Proc. Conf. Ordinary Diff. Equations, Poprad 1994, pp. 23–31.
[6] O. Došlý:
Oscillation criteria for self-adjoint linear differential equations. Math. Nachr. 166 (1994), 141–153.
DOI 10.1002/mana.19941660112
[10] O. Došlý and F. Fiedler:
A remark on Nehari-type criteria for self-adjoint differential equations. Comment. Math. Univ. Carolin. 32 (1991), 447–462.
MR 1159793
[11] O. Došlý and J. Komenda:
Principal solutions and conjugacy criteria for self-adjoint differential equations. Arch. Math. 31 (1995), 217–238.
MR 1368260
[12] O. Došlý and J. Osička:
Kneser-type oscillation criteria for self-adjoint, two term, differential equations. Georgian J. Math. 2 (1995), 241–258.
MR 1334880
[13] F. Fiedler:
Oscillation criteria for a class of $2n$-order ordinary differential operators. J. Differential Equations 42 (1982), 155–185.
MR 0641646
[15] I. M. Glazman: Direct Methods of Qualitative Analysis of Singular Differential Operators. Davey, Jerusalem, 1965.
[16] D. B. Hinton and R. T. Lewis:
Discrete spectra criteria for singular differential operators with middle terms. Math. Proc. Cambridge Philos. Soc. 77 (1975), 337–347.
DOI 10.1017/S0305004100051161 |
MR 0367358
[17] D. B. Hinton and R. T. Lewis:
Singular differential operators with spectra discrete and bounded below. Proc. Roy. Soc. Edinburgh 84A (1979), 117–134.
MR 0549875
[18] W. Kratz:
Quadratic Functionals in Variational Analysis and Control Theory. Akademie Verlag, Berlin, 1995.
MR 1334092 |
Zbl 0842.49001
[19] W. T. Reid:
Sturmian Theory for Ordinary Differential Equations. Springer Verlag, New York-Heidelberg-Berlin, 1980.
MR 0606199 |
Zbl 0459.34001