Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh quang
hieu suat » hieu luat, hieu qua
quang doi » quan doi, quang hoi, quang do
quang dai » quang dam, quang hai, quang ngai
van hieu » cao hieu
tin dang » tin dung, tin nang, tin mang
bien so » bien doi
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: (( tinh dung luan van hieu suat ) or ( tin dang ((quang doi) OR (quang dai)) bien so ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung luan van hieu suat ) OR ( tin dang ((quang doi) OR (quang dai)) bien so )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung luan van hieu suat ) or ( tin dang ((quang doi) OR (quang dai)) bien so ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung luan van hieu suat ) or ( tin dang ((quang doi) OR (quang dai)) bien so ))*.