Perhaps you should try some spelling variations:
hieu soat » hieu suat, hieu hoat, hieu luat
dan quang » dang quang, doan quang, van quang
quang van » quang ban, quan van, quang uan
hien soan » bien soan, thien toan, dien toan
dung lan » dung luan, dung land, dung san
dung lam » dung luan, dung tai, dung dat
binh dan » minh danh, binh dinh, binh luan
van hien » van hieu, van tien

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh ((dung lan) or (dung lam)) cao hieu soat ) or ( binh dan quang van hien soan ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh ((dung lan) OR (dung lam)) cao hieu soat ) OR ( binh dan quang van hien soan )).
• Adding a wildcard symbol may retrieve word variants: (( tinh ((dung lan) or (dung lam)) cao hieu soat ) or ( binh dan quang van hien soan ))*.