Perhaps you should try some spelling variations:
quang quan » quang tuan, quang uan, quan quan
dung ltan » dung luan, dung tai, dung nhan
hieu suat » hieu luat, hieu qua
kien soat » kiem soat, bien soan, kien hoa
ltan van » luan van, tan van, lan van
van hieu » cao hieu
quan van » luan van, quan va, quan luan
van kien » van tien, van hien, van chien

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