Perhaps you should try some spelling variations:
huong quan » luong quan, cuong quan, hong quan
vuong quan » luong quan, cuong quan, luong quang
hieu soat » hieu suat, hieu hoat, hieu luat
dung quan » dung quang, dung luan, luong quan
luan kien » xuan kien, luan lien, quan kien
van hieu » cao hieu
kien ha » kien hoa, kien va, dien hoa

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 ((huong quan) OR (vuong quan)) van hieu soat ) OR ( trinh dung quan luan kien ha ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh ((huong quan) OR (vuong quan)) van hieu soat ) or ( trinh dung quan luan kien ha ))~".
• Adding a wildcard symbol may retrieve word variants: (( tinh ((huong quan) OR (vuong quan)) van hieu soat ) or ( trinh dung quan luan kien ha ))*.