Columbia subject headings:
Copyright--Germany.
Copyright--United States.
Patents--Germany.
Patents--United States.
Harvard subject headings:
Copyright infringement--Germany.
Copyright infringement--United States.
Estoppel--Germany.
Estoppel--United States.
Patent infringement--Germany.
Patent infringement--United States.
Time (Law)--Germany.
Time (Law)--United States.
Princeton subject headings: