Perhaps you should try some spelling variations:
dong hoang » hong hong
how gender » do gender
gender yan » gender a, gender am, gender das
yang yang » wang yang, wang yan
wong sau » wong sam, wong siu, wong shiu
hong ghi » zhong zhi, hong g, hong hai
yan jiu » yang jie, yang jin, pang jiu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((yang yang) or (dong hoang)) asia how gender yan jiu ((wong sau) or (hong ghi)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((yang yang) OR (dong hoang)) asia how gender yan jiu ((wong sau) OR (hong ghi)) ;.
• Adding a wildcard symbol may retrieve word variants: ((yang yang) or (dong hoang)) asia how gender yan jiu ((wong sau) or (hong ghi)) ;*.