Perhaps you should try some spelling variations:
dang quang » dung quang, nang quan, dang hung
quang quan » quang tuan, quang uan, quan quan
tinh dang » tinh dung, binh dang, tinh sang
quang van » quang ban, quang uan, quang va
hieu suat » hieu luat, hieu qua
kiem soat » kiem toan
van hieu » cao hieu
quan van » luan van, quan va, quan luan
van kiem » va kiem, van kien, van hien

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh dang quang van hieu suat ) or ( tinh quang quan van kiem soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dang quang van hieu suat ) OR ( tinh quang quan van kiem soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh dang quang van hieu suat ) or ( tinh quang quan van kiem soat ))*.