Perhaps you should try some spelling variations:
dang quang » dung quang, nang quan, dang hung
hieu soat » hieu hoat, hieu luat, kiem soat
hieu suat » hieu luat, hieu qua
bien soan » bien so
tin dang » tin dung, tin nang, tin mang
quang va » quang van, quan va, quang ma
va bien » vat bien, va lien, va dien
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 soat) OR (hieu suat)) ) OR ( tin dang quang va bien soan ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( trinh dung luan van ((hieu soat) OR (hieu suat)) ) or ( tin dang quang va bien soan ))~".
• Adding a wildcard symbol may retrieve word variants: (( trinh dung luan van ((hieu soat) OR (hieu suat)) ) or ( tin dang quang va bien soan ))*.