Patent US2777901A successfully refreshed from Google Patents.
US2777901A
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US
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Binaural apparatus for teaching languages
Assignee: Individual
•
Filing: 1951-11-07
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Granted: 1957-01-15
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Expires: 1971-11-07
Abstract
No abstract record available.
Inventors
- 👤 Leon E Dostert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:17
CPC Classifications
G; G09; G09B; G09B5/00; G09B5/04
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
FR396518A
Cited
US1229142A
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US2126370A
Cited
GB377276A
Cited
GB393052A
Cited
US2237738A
Cited
US2209157A
Cited
US2416353A
Cited
US2554582A
Cited
US2764639A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1960-01-15 | 1960-07-16 | 1961-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-01-15 | 1964-07-16 | 1965-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-01-15 | 1968-07-16 | 1969-01-15 | $7700.00 | Window Closed / Lapsed |