Granted Patent
Utility
US 4,275,273 · App. 06/010,375
Telephone index for repertory dialer
Inventor:
Si-Ling Ts'ao
Patented Case
View Patent ↗
Granted: Jun 23, 1981
Filed: Feb 8, 1979
Inventor
Si-Ling Ts'ao
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.