Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
dung quan » dung quang, dung luan, luong quan
hieu suat » hieu luat, hieu qua
quang uan » quang tuan, quang ban, quang tran
van hieu » cao hieu
quan va » quan vi, quan ha, luan va
va hieu » va dieu, va hien, cao hieu
uan van » luan van, quan van, tan 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 va hieu suat ) or ( tinh quang uan van hieu suat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung quan va hieu suat ) OR ( tinh quang uan van hieu suat ))*.