Perhaps you should try some spelling variations:
dinh quan » dinh quang, dinh xuan, dinh duan
trinh han » trinh quan
hieu suat » hieu luat, hieu qua
han quan » phan quan, hang quan, van quan
quan voi » quan doi, quan vi, quen voi
voi bien » vat bien, va bien, ve bien
van hieu » cao hieu
bien so » bien doi
luan » lan

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh han quan voi bien so ) or ( dinh quan luan van hieu suat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh han quan voi bien so ) OR ( dinh quan luan van hieu suat ))*.