Perhaps you should try some spelling variations:
dung qluan » dung luan, dung quan, dung quang
quang luan » quan luan, quang tuan, quang uan
tinh dung » trinh dung, tin dung, tinh huong
qluan van » quan van, luan va, quan va
hieu suat » hieu luat
hieu soat » hieu hoat, hieu luat, kiem soat
van hieu » cao hieu

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 qluan van ((hieu suat) or (hieu qua)) ) or ( tinh quang luan van hieu soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung qluan van ((hieu suat) OR (hieu qua)) ) OR ( tinh quang luan van hieu soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh dung qluan van ((hieu suat) or (hieu qua)) ) or ( tinh quang luan van hieu soat ))*.