Perhaps you should try some spelling variations:
trinh quan » tinh quang, trinh luat, trinh han
quan quang » qua quang, quan quan, quat quang
quang doi » quan doi, quang hoi, quang dai
hieu suat » hieu luat, hieu qua
bien soan » bien so
doi hieu » doi chieu, doc hieu, doi hien
binh dan » minh danh, binh dinh, binh luan
dan dung » van dung, tin dung, ap dung
dung van » duong van, dung va, dang van
van bien » van tien, van hien, vat bien

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh quan quang doi hieu suat ) or ( binh dan dung van bien soan ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh quan quang doi hieu suat ) OR ( binh dan dung van bien soan )).
• Adding a wildcard symbol may retrieve word variants: (( trinh quan quang doi hieu suat ) or ( binh dan dung van bien soan ))*.