Perhaps you should try some spelling variations:
tinh khung » trinh khung, tinh hung, tinh khang
quang quan » quang tuan, quang uan, quan quan
khung luan » chung luan, dung luan, hang luan
hieu soat » hieu suat, hieu hoat, hieu luat
van hieu » cao hieu
quan va » quan vi, quan ha, luan va
va hieu » va dieu, va hien, cao hieu
toan » tran

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 quan va hieu soat ) or ( tinh khung luan ((van hieu) or (toan tien)) soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang quan va hieu soat ) OR ( tinh khung luan ((van hieu) OR (toan tien)) soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh quang quan va hieu soat ) or ( tinh khung luan ((van hieu) or (toan tien)) soat ))*.