Perhaps you should try some spelling variations:
duong anh » dang anh, trong anh
duong van » cong van
john wong » john song, john bonn
tran hua » tan hua, tuan hua, tran duc
ren yang » chen yang, dan yang, ren weng
pei yang » wei yang, hui yang, pei yun
wong sam » wong sau, wong lai, kong sar

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: ((duong anh) OR (duong van)) tran hua ((((ren yang) OR (pei yang))) OR (ren yan)) john wong sam ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((duong anh) OR (duong van)) tran hua ((((ren yang) or (pei yang))) or (ren yan)) john wong sam ;~".
• Adding a wildcard symbol may retrieve word variants: ((duong anh) OR (duong van)) tran hua ((((ren yang) or (pei yang))) or (ren yan)) john wong sam ;*.