Perhaps you should try some spelling variations:
dong yang » dong hoang, wang yang, yang yang
dong nan » dong sin, dong bin, dong cao
a patent » a patient, _ patent, a parent
long du » long do, long run, long did
long d » long do, long _, long 2
a bau » a bad, a bab, a ban
ya a » a a, y a, ye a
a au » a auf, a aus, a a

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((dong nan) OR (dong yang)) ya a patent ((a au) OR (a bau)) ((long du) OR (long d)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((dong nan) or (dong yang)) ya a patent ((a au) OR (a bau)) ((long du) or (long d)) ;~".
• Adding a wildcard symbol may retrieve word variants: ((dong nan) or (dong yang)) ya a patent ((a au) OR (a bau)) ((long du) or (long d)) ;*.