共 50 条
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- [36] OSCILLATION CRITERIA FOR SYSTEMS OF LINEAR DIFFERENTIAL EQUATIONS NOTICES OF THE AMERICAN MATHEMATICAL SOCIETY, 1971, 18 (02): : 370 - &
- [38] CRITERIA FOR DISCRETE SPECTRUM OF SINGULAR SELFADJOINT DIFFERENTIAL OPERATORS NOTICES OF THE AMERICAN MATHEMATICAL SOCIETY, 1971, 18 (07): : 1057 - &