Perhaps you should try some spelling variations:
quang lam » quang nam, dung lam, quang cao
hieu soat » hieu suat, hieu hoat, hieu luat
tien soat » trien hoat, thien hoat, kiem soat
van hieu » cao hieu
van tien » toan tien, van tuan
lam van » lam san, nam van, dam van
tinh » trinh, dinh, minh
luan » quan, lan

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh quang lam van hieu soat ) or ( tin dung luan van tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang lam van hieu soat ) OR ( tin dung luan van tien soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh quang lam van hieu soat ) or ( tin dung luan van tien soat ))*.