Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
hieu soat » hieu suat, hieu hoat, hieu so
hieu luat » hieu qua
quang uan » quang tuan, quang ban, quang tran
kiem soat » kiem toan
van kiem » va kiem, van kien, van hieu
tai van » thai van, thi van, tai san
uan van » luan van, quan van, tan van

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 tai van ((hieu soat) OR (hieu luat)) ) OR ( tinh quang uan van kiem soat ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung tai van ((hieu soat) OR (hieu luat)) ) or ( tinh quang uan van kiem soat ))~".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung tai van ((hieu soat) OR (hieu luat)) ) or ( tinh quang uan van kiem soat ))*.