Perhaps you should try some spelling variations:
dung quan » dung quang, dung luan, luong quan
tinh dung » trinh dung, tinh quang, tinh huong
hieu hoat » hieu hoa, thien hoat, hieu suat
hieu luat » hieu qua
dung tan » dung toan, duong tan, dung tai
quan cao » quang cao, quan cau, quan ao
va kiem » van kien
tan va » tan van, toan va, than va

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 tan va kiem tra ) or ( tinh dung quan cao ((hieu hoat) or (hieu luat)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dung tan va kiem tra ) OR ( tinh dung quan cao ((hieu hoat) OR (hieu luat)) )).
• Adding a wildcard symbol may retrieve word variants: (( tin dung tan va kiem tra ) or ( tinh dung quan cao ((hieu hoat) or (hieu luat)) ))*.