Perhaps you should try some spelling variations:
dung quang » dang quang, dung quan, luong quang
quang luan » quan luan, quang tuan, quang uan
quang cao » nang cao, quang nam
hieu suat » hieu luat, hieu qua
kiem soat » kiem toan
luan va » luan van, luat va
va kiem » van kien

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 quang cao hieu suat ) or ( tinh quang luan va kiem soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung quang cao hieu suat ) OR ( tinh quang luan va kiem soat )).
• Adding a wildcard symbol may retrieve word variants: (( trinh dung quang cao hieu suat ) or ( tinh quang luan va kiem soat ))*.