Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
dung qtan » dung quan, dung quang, dung tai
hieu soat » hieu suat, hieu hoat, hieu luat
quang tan » quang tuan, quang tran, quang toan
bien soan » bien so
qtan van » quan van, quang van, luan van
van hieu » cao hieu
van bien » van tien, van hien, vat bien
tan van » tran van, tang van, luan 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 qtan van hieu soat ) or ( tinh quang tan van bien soan ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung qtan van hieu soat ) OR ( tinh quang tan van bien soan )).
• Adding a wildcard symbol may retrieve word variants: (( tinh dung qtan van hieu soat ) or ( tinh quang tan van bien soan ))*.