Perhaps you should try some spelling variations:
dung quan » dung quang, dung luan, luong quan
dieu suat » hieu suat, trieu suat, hieu luat
quang tan » quang tuan, quang tran, quang toan
kien soat » kiem soat, bien soan, kien hoa
van kien » van tien, van hien, van chien
quan va » quan vi, quan ha, luan va
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: (( tin dung quan va dieu suat ) or ( tinh quang tan van kien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dung quan va dieu suat ) OR ( tinh quang tan van kien soat ))*.