Perhaps you should try some spelling variations:
luong quan » duong qua
tinh dung » trinh dung, tin dung, tinh quang
dung quan » dung quang, dung luan, dang quang
hieu luat » hieu qua
kien soat » kiem soat, bien soan, kien hoa
quan doi » quan tri, quan li
doi hieu » doi chieu, doc hieu, doi hien
van kien » van tien, van hien, van chien

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 doi hieu luat ) OR ( tinh ((luong quan) OR (thong quan)) van kien soat ))~.
• Adding a wildcard symbol may retrieve word variants: (( tinh dung quan doi hieu luat ) or ( tinh ((luong quan) or (thong quan)) van kien soat ))*.