Perhaps you should try some spelling variations:
quang tang » quang thang, quang dang, quang tung
dung lang » dung dang, dung nang, dung land
hieu suat » hieu luat
hien soat » thien hoat, kiem soat, bien soan
lang cao » nang cao, lang co, quang cao
tang van » dang van, hoang van, trong van
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: (( tin dung lang cao ((hieu suat) or (hieu qua)) ) or ( tinh quang tang van hien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dung lang cao ((hieu suat) OR (hieu qua)) ) OR ( tinh quang tang van hien soat )).
• Adding a wildcard symbol may retrieve word variants: (( tin dung lang cao ((hieu suat) or (hieu qua)) ) or ( tinh quang tang van hien soat ))*.