Perhaps you should try some spelling variations:
dang quang » nang quan, dang hung
dung quang » dung quan, luong quang, dung ung
hieu suat » hieu luat, hieu qua
binh hien » minh hien, kinh hien, dinh hien
hien soat » thien hoat, kiem soat, bien soan
van hieu » cao hieu
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: (( trinh dung luan van hieu suat ) OR ( dinh ((dang quang) OR (dung quang)) binh hien soat ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( trinh dung luan van hieu suat ) or ( dinh ((dang quang) OR (dung quang)) binh hien soat ))~".
• Adding a wildcard symbol may retrieve word variants: (( trinh dung luan van hieu suat ) or ( dinh ((dang quang) OR (dung quang)) binh hien soat ))*.