Perhaps you should try some spelling variations:
chien soat » thien hoat
tinh dung » trinh dung, tin dung, tinh quang
hieu suat » hieu luat, hieu qua
dung quan » dung quang, dung luan, luong quan
van chien » van hien, van tien
dung san » dong san, dung sai, dung luan
van hieu » cao hieu
quan van » luan van, quan va, quan luan
san van » tan van, luan van, tran van

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 san van hieu suat ) or ( tinh dung quan van chien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung san van hieu suat ) OR ( tinh dung quan van chien soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh dung san van hieu suat ) or ( tinh dung quan van chien soat ))*.