USD317787SExpiredUtility

Mathematical aid

30
Individually held — no corporate assignee on recordPriority: Aug 22, 1989Filed: Feb 21, 1990Granted: Jun 25, 1991
Est. expiryAug 22, 2009(expired)· nominal 20-yr term from priority
Inventors:William A. DavidsonSilvia DavidsonJohn D. Charters
30
PatentIndex Score
3
Cited by
1
References
1
Claims

Claims

exact text as granted — not AI-modified
The ornamental design of a mathematical aid, as shown and described.

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