[1] |
M. M. Gekhtman, ?Self-adjointness of abstract differential operators,? Matem. Zametki,6, No. 1, 65-72 (1969). |
[2] |
L. I. Vainerman and M. L. Gorbachuk, ?Self-adjointness of semibounded abstract differential operators,? Ukrainsk. Matem. Zh.,22, No. 6, 794-797 (1970). |
[3] |
L. I. Vainerman and M. L. Gorbachuk, ?Direct methods of qualitative spectral analysis for Sturm-Liouville equation with unbounded operator potential,? Dopovidi Akad. Nauk UkrSSR, Ser. A, No. 7, 583-585 (1972). |
[4] |
M. M. Gekhtman, ?Spectrum of the Sturm-Liouville operator equation,? Funktsional’. Anauz i Ego Prilozhen.,6, No. 2, 81-82 (1972). |
[5] |
A. N. Kochubei, ?Self-adjointness and the nature of the spectrum of certain classes of abstract differential operators,? Ukrainsk. Matem. Zh.,25, No. 6, 811-815 (1973). |
[6] |
A. N. Kochubei, ?From self-adjointness to J-self-adjointness of abstract differential operators,? Dokl. Akad. Nauk URSR, Ser. A, No. 7, 602-604 (1973). |
[7] |
M. Schechter, Spectra of Partial Differential Operators, North Holland, Amsterdam (1971). · Zbl 0225.35001 |
[8] |
B. Simon, ?Essential self-adjointness of Schrödinger operators with positive potentials,? Math. Ann.,201, No. 3, 211-220 (1973). · Zbl 0234.47027 · doi:10.1007/BF01427943 |
[9] |
T. Ikebe and T. Kato, ?Uniqueness of the self-adjoint extension of singular elliptic operators,? Arch. Rat. Mech. Anal.,9, No. 1, 77-92 (1962). · Zbl 0103.31801 · doi:10.1007/BF00253334 |
[10] |
E. Nelson, ?Feynman integrals and the Schrödinger equation,? J. Math. Phys.,5, No. 3, 332-343 (1964). · Zbl 0133.22905 · doi:10.1063/1.1704124 |
[11] |
W. Faris, ?The product formula for semigroups defined by Friedrichs’extension,? Pacific J. Math.,22, No. 1, 47-70 (1967). · Zbl 0158.14802 |
[12] |
Yu. M. Berezanskii, Expansions in Eigenfunctions of Self-Adjoint Operators [in Russian], Naukova Dumka, Kiev (1965). |
[13] |
M. L. Gorbachuk and A. N. Kochubei, ?Self-adjoint boundary-value problems for certain classes of differential-operator equations of high order,? Dokl. Akad. Nauk SSSR,201, No. 5, 1029-1032 (1971). |
[14] |
M. A. Krasnosel’skii, P. P. Zabreiko, E. I. Pustyl’nik, and P. E. Sobolevskii, Integral Operators on Spaces of Summable Functions [in Russian], Nauka, Moscow (1966). |
[15] |
A. K. Sushkevich, Fundamentals of Higher Algebra [in Russian], Gostekhizdat, Moscow (1941). |
[16] |
V. I. Gorbachuk and M. L. Gorbachuk, ?Questions in the spectral theory of linear second-order differential equations with unbounded operator coefficients,? Ukrainsk. Matem. Zh.,23, No. 1, 3-15 (1971). |
[17] |
L. Hörmander, ?On the theory of general partial differential operators,? Acta Math.,94, 161-248 (1955). · Zbl 0067.32201 · doi:10.1007/BF02392492 |
[18] |
R. S. Ismagilov, ?Conditions for the self-adjointness of high-order differential operators,? Dokl. Akad. Nauk SSSR,142, No. 6, 1239-1242 (1962). · Zbl 0119.07203 |
[19] |
M. G. Gimadislamov, ?Conditions for self-adjointness of high-order differential operators with operator coefficients,? Matem. Zametki,5, No. 6, 697-709 (1969). · Zbl 0187.07803 |
[20] |
A. G. Brusentsev and F. S. Rofe-Beketov, ?Conditions for self-adjointness of high-order elliptic operators,? in: Mathematical Physics and Functional Analysis [in Russian], No. 2, FIINT Akad. Nauk UkrSSR, Khar’kov (1971), pp. 15-25. |
[21] |
E. Wienholtz, ?Halbbeschränkte partielle Differential-operatoren zweiter Ordnung vom elliptischen Typus,? Math. Ann.,135, No. 1, 50-80 (1958). · Zbl 0142.37701 · doi:10.1007/BF01350827 |
[22] |
F. Rellich, ?Störungstheorie der Spectralzerlegung, III,? Math. Ann.,116, 555-570 (1939). · JFM 65.0510.01 · doi:10.1007/BF01597374 |
[23] |
T. Kato, Perturbation Theory for Linear Operators, Third Edition, Springer, Berlin (1976). · Zbl 0342.47009 |