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 _
lam long » a long
au long » a long, eu long, amp long
ye a » yet a, e a, me 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 cao) OR (dong yang)) ye a patent a ((au long) OR (lam long)) du ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((dong cao) or (dong yang)) ye a patent a ((au long) OR (lam long)) du ;~".
• Adding a wildcard symbol may retrieve word variants: ((dong cao) or (dong yang)) ye a patent a ((au long) OR (lam long)) du ;*.