Perhaps you should try some spelling variations:
luong quan » thong quan, duong qua
tinh dung » trinh dung, tin dung, tinh quang
dung quan » dung quang, dung luan, dang quang
hieu soat » hieu suat, hieu hoat, hieu luat
tuan tien » toan tien, tran tien, thang tien
tien soan » bien soan, tien hoang, thien toan
van hieu » cao hieu
va tuan » van tuan, va quan, va toan

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 quan) OR (luong quan)) van hieu soat ) OR ( tinh dung va tuan tien soan ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh ((dung quan) OR (luong quan)) van hieu soat ) or ( tinh dung va tuan tien soan ))~".
• Adding a wildcard symbol may retrieve word variants: (( tinh ((dung quan) OR (luong quan)) van hieu soat ) or ( tinh dung va tuan tien soan ))*.