IP Library › Granted Patent US 4,933,871
Granted Patent Utility
US 4,933,871 · App. 07/287,877

Graded learning device and method

Inventor: Duane DeSieno
Patented Case View Patent ↗
Granted: Jun 12, 1990 Filed: Dec 21, 1988
Inventor
Duane DeSieno

This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.

Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 4,933,871
App. No.
07/287,877
Filed
1988-12-21
Granted
1990-06-12
Kind
A