Perhaps you should try some spelling variations:
than china » tuan china, han china, wuhan china
china gene » china gender, china agenda
yan than » van thanh, yan zhang, yan clan
wong sam » wong sau, wong lai, kong sar
wong siu » wong shiu, kong siu, wong sau
yang yi » yang xi, yang jui
wang » wing, wan, lang

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: wang yan than china gene ((yang yi) OR (yang di)) ((wong sam) OR (wong siu)) ;~.
• Adding a wildcard symbol may retrieve word variants: wang yan than china gene ((yang yi) or (yang di)) ((wong sam) or (wong siu)) ;*.