Perhaps you should try some spelling variations:
quang quan » quang tuan, quang uan, quan quan
dung ltan » dung luan, dung nhan, dung ngan
hieu suat » hieu luat, hieu qua
kiem soat » kiem toan
van hieu » cao hieu
quan van » luan van, quan va, quan luan
van kiem » va kiem, van kien, van hien

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