Perhaps you should try some spelling variations:
quang thanh » quan thanh, hoang thanh, muong thanh
quang quan » quang tuan, quang uan, quan quan
hieu suat » hieu luat, hieu qua
kiem soat » kiem toan
quan van » luan van, quan va, quan doan
van hieu » cao hieu
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: (( tinh quang quan van hieu suat ) or ( tinh ((quang thanh) or (quan luan)) va kiem soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang quan van hieu suat ) OR ( tinh ((quang thanh) OR (quan luan)) va kiem soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh quang quan van hieu suat ) or ( tinh ((quang thanh) or (quan luan)) va kiem soat ))*.