Perhaps you should try some spelling variations:
dong yang » dong hoang, wang yang, yang yang
dong cao » dong xiao, dan cao, dong nan
a patent » a patient, _ patent, a parent
patent a » patient a, patents a, patent _
au long » a long, eu long, lam long
long du » long d, long do, long run
ya a » a a, y a, ye a
a au » a auf, a bau, a aus

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((dong cao) or (dong yang)) ya a patent a au long du ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((dong cao) OR (dong yang)) ya a patent a au long du ;.
• Adding a wildcard symbol may retrieve word variants: ((dong cao) or (dong yang)) ya a patent a au long du ;*.