Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh quang
dung quan » dung quang, dung luan, luong quan
hieu soat » hieu hoat, hieu luat, hieu so
hieu suat » hieu luat, hieu qua
kiem soat » kiem toan
quan cao » quang cao, quan cau, quan ao
tinh ban » tinh bang, trinh ban, tinh bac
ban quan » van quan
quan van » luan van, quan va, quan luan
van kiem » va kiem, van kien, van hieu

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: (( tinh dung quan cao ((hieu soat) OR (hieu suat)) ) OR ( tinh ban quan van kiem soat ))~.
• Adding a wildcard symbol may retrieve word variants: (( tinh dung quan cao ((hieu soat) or (hieu suat)) ) or ( tinh ban quan van kiem soat ))*.