Perhaps you should try some spelling variations:
dung quan » dung quang, luong quan, dang quang
hieu suat » hieu luat, hieu qua
tinh dung » tin dung, tinh quang, tinh huong
bien soan » bien so
van bien » van tien, van hien, vat bien
quan vi » quan li, quan tri, quan doi
vi hieu » vi dieu, va hieu, vo hieu
luan » 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: (( trinh dung quan vi hieu suat ) OR ( tinh dung luan van bien soan ))~.
• Adding a wildcard symbol may retrieve word variants: (( trinh dung quan vi hieu suat ) or ( tinh dung luan van bien soan ))*.