Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh huong
dung quan » dung quang, dung luan, luong quan
hieu suat » hieu luat, hieu qua
tien soat » trien hoat, thien hoat, kiem soat
quan van » luan van, quan va, quan luan
van hieu » cao hieu
cua van » cua ban, cua dan, cua can

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh dung quan van hieu suat ) or ( tinh quang ((cua van) OR (cua vat)) tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung quan van hieu suat ) OR ( tinh quang ((cua van) OR (cua vat)) tien soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung quan van hieu suat ) or ( tinh quang ((cua van) OR (cua vat)) tien soat ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung quan van hieu suat ) or ( tinh quang ((cua van) OR (cua vat)) tien soat ))*.