Granted Patent
Utility
US 4,431,671 · App. 06/326,998
Phenylureas
Inventor:
Josef Ehrenfreund
Patented Case
View Patent ↗
Granted: Feb 14, 1984
Filed: Dec 3, 1981
Inventor
Josef Ehrenfreund
Assignee (at issue)
Ciba-Geigy
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.