Perhaps you should try some spelling variations:
tinh quan » tinh quang, trinh quan, tin quan
quan quan » quan quang, qua quan, quan luan
hieu suat » hieu luat, hieu qua
quan van » luan van, quan va, quan luan
van hieu » cao hieu
tinh quy » dinh quy, minh quy, hinh quy
luat may » luat xay, luat day, thuat may
tinh hoa » trinh hoa, tinh hoc, minh hoa

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

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