共 50 条
[12]
DISCONJUGACY CRITERIA FOR NONSELFADJOINT DIFFERENTIAL EQUATIONS OF EVEN ORDER
[J].
NOTICES OF THE AMERICAN MATHEMATICAL SOCIETY,
1970, 17 (05)
:776-&
[20]
CRITERIA FOR DISCRETE SPECTRUM OF SINGULAR SELFADJOINT DIFFERENTIAL OPERATORS
[J].
NOTICES OF THE AMERICAN MATHEMATICAL SOCIETY,
1971, 18 (07)
:1057-&