Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh quang
hieu suat » hieu luat, hieu qua
quang uan » quang tuan, quang tran, quang chan
quang ban » quang binh, quang tuan, quang tran
kien soat » kiem soat, bien soan, kien hoa
dung lan » dung luan, dung land, dung lam
van hieu » cao hieu
van kien » van tien, van hien, van chien
lan van » luan van, lang van, tan 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 lan van hieu suat ) OR ( tinh ((quang uan) OR (quang ban)) van kien soat ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung lan van hieu suat ) or ( tinh ((quang uan) OR (quang ban)) van kien soat ))~".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung lan van hieu suat ) or ( tinh ((quang uan) OR (quang ban)) van kien soat ))*.