Perhaps you should try some spelling variations:
dung quang » dang quang, dung quan, luong quang
hieu soat » hieu suat, hieu hoat, hieu luat
tinh dung » tin dung, tinh quang, tinh huong
binh hien » minh hien, kinh hien, tinh hien
dinh hien » dinh chien, dinh dien, minh hien
van hieu » cao hieu
luan » quan, lan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh dung luan van hieu soat ) or ( tinh dung quang ((binh hien) OR (dinh hien)) soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung luan van hieu soat ) OR ( tinh dung quang ((binh hien) OR (dinh hien)) soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( trinh dung luan van hieu soat ) or ( tinh dung quang ((binh hien) OR (dinh hien)) soat ))".
• Adding a wildcard symbol may retrieve word variants: (( trinh dung luan van hieu soat ) or ( tinh dung quang ((binh hien) OR (dinh hien)) soat ))*.