Perhaps you should try some spelling variations:
sang quang » dang quang, hang quang, tang quang
hieu soat » hieu hoat, hieu luat, hieu so
hieu suat » hieu luat, hieu qua
tinh sang » tinh quang, tinh trang, trinh san
kiem soat » kiem toan
quang va » quang van, quan va, quang ma
va kiem » van kien
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 (hieu suat)) ) or ( tinh sang quang va kiem soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung luan van ((hieu soat) OR (hieu suat)) ) OR ( tinh sang quang va kiem soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( trinh dung luan van ((hieu soat) OR (hieu suat)) ) or ( tinh sang quang va kiem soat ))".
• Adding a wildcard symbol may retrieve word variants: (( trinh dung luan van ((hieu soat) OR (hieu suat)) ) or ( tinh sang quang va kiem soat ))*.