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

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 (yang yang)) ya a patent a eu long du ;~.
• Adding a wildcard symbol may retrieve word variants: ((dong cao) or (yang yang)) ya a patent a eu long du ;*.