Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
hieu suat » hieu luat, hieu qua
quang uan » quang tuan, quang ban, quang tran
kien soat » kiem soat, bien soan, kien hoa
quan van » luan van, quan luan, quan doan
van kien » van tien, van hien, van chien
quan va » quan vi, quan ha, luan va
uan van » luan van, tan van, san van

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 ((quan van) OR (quan va)) hieu suat ) or ( tinh quang uan van kien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung ((quan van) OR (quan va)) hieu suat ) OR ( tinh quang uan van kien soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung ((quan van) OR (quan va)) hieu suat ) or ( tinh quang uan van kien soat ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung ((quan van) OR (quan va)) hieu suat ) or ( tinh quang uan van kien soat ))*.