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, dang quang, dung cua
hieu soat » hieu suat, hieu hoat, hieu luat
van hieu » cao hieu
van bien » van tien, van hien, vat bien
bien so » bien doi
luan » lan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh ((dung quan) or (luong quan)) van hieu soat ) or ( tinh dung luan van bien so ))~.
• 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 luan van bien so )).
• Adding a wildcard symbol may retrieve word variants: (( tinh ((dung quan) or (luong quan)) van hieu soat ) or ( tinh dung luan van bien so ))*.