Perhaps you should try some spelling variations:
luong quang » dung quang
luong quan » duong qua
tinh thong » tinh thuong, trinh thong, tinh khong
hieu soat » hieu suat, hieu hoat, hieu luat
van hieu » cao hieu
quan vi » quan li, quan tri, quan doi
vi hieu » vi dieu, va hieu, vo hieu

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