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 lai, kong sar, wong max
wong sau » wong siu, wong shiu, wong lai
von sam » von sa, von sap, von scham
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 judy) OR (yang di)) ((((wong sam) OR (von sam))) OR (wong sau)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wang yan than china gene ((yang judy) or (yang di)) ((((wong sam) OR (von sam))) or (wong sau)) ;~".
• Adding a wildcard symbol may retrieve word variants: wang yan than china gene ((yang judy) or (yang di)) ((((wong sam) OR (von sam))) or (wong sau)) ;*.