Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
hieu suat » hieu qua
hieu luat » hieu qua
quang van » quang ban, quan van, quang uan
kien soat » kiem soat, bien soan, kien hoa
van kien » van tien, van hien, van chien
van van » van ban, tan van, san van
luan » quan, lan

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