Perhaps you should try some spelling variations:
quang tran » quang tuan, quang trung, quang thanh
hieu suat » hieu luat, hieu qua
tinh dung » trinh dung, tin dung, tinh huong
dung quan » dung quang, dung luan, luong quan
tran van » luan van
van hieu » cao hieu
quan van » luan van, quan va, quan luan
van tin » van tien, van tan, van thinh
tin so » tinh son

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh quang tran van hieu suat ) or ( tinh dung quan van tin so ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang tran van hieu suat ) OR ( tinh dung quan van tin so ))*.