Perhaps you should try some spelling variations:
trinh quan » tinh quang, trinh luat, trinh han
tinh dung » trinh dung, tinh quang, tinh huong
hieu suat » hieu luat, hieu qua
quan doan » quan hoang, chuan doan, chan doan
tien soat » trien hoat, thien hoat, kiem soat
van hieu » cao hieu
doan van » doan va, hoang van, luan van
van tien » toan tien, van tuan
tan van » tran van, tang van, luan van

You may be able to get more results by adjusting your search query.

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