Perhaps you should try some spelling variations:
trinh cong » trinh dung
tinh dung » trinh dung, tin dung, tinh quang
hieu soat » hieu suat, hieu hoat, hieu luat
tinh cong » tinh cuong, minh cong, sinh cong
hien soat » thien hoat, kiem soat, bien soan
van hieu » cao hieu
van hien » van tien

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 soat ) or ( ((tinh cong) OR (trinh cong)) luan van hien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung luan van hieu soat ) OR ( ((tinh cong) OR (trinh cong)) luan van hien soat ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung luan van hieu soat ) or ( ((tinh cong) OR (trinh cong)) luan van hien soat ))*".