Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
dung quan » dung quang, dung luan, luong quan
hieu soat » hieu suat, hieu hoat, kiem soat
hieu luat » hieu qua
quang uan » quang tuan, quang ban, quang tran
bien soan » bien so
quan van » luan van, quan va, quan luan
van bien » van tien, van hien, vat bien
uan van » luan van, tan van, san van

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 van ((hieu soat) OR (hieu luat)) ) or ( tinh quang uan van bien soan ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung quan van ((hieu soat) OR (hieu luat)) ) OR ( tinh quang uan van bien soan )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung quan van ((hieu soat) OR (hieu luat)) ) or ( tinh quang uan van bien soan ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung quan van ((hieu soat) OR (hieu luat)) ) or ( tinh quang uan van bien soan ))*.