Perhaps you should try some spelling variations:
tinh dung » trinh dung, tin dung, tinh quang
dung quan » dung quang, dung luan, luong quan
hieu suat » hieu luat, hieu qua
tinh dang » binh dang, tinh sang, dinh dang
hien soat » thien hoat, kiem soat, bien soan
quan van » luan van, quan va, quan luan
van hieu » cao hieu

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