Perhaps you should try some spelling variations:
tinh thong » tinh thuong, trinh thong, tinh khong
quang luan » quan luan, quang tuan, quang uan
hieu soat » hieu hoat, hieu luat, kiem soat
hieu suat » hieu luat, hieu qua
hien soat » thien hoat, kiem soat, bien soan
quan van » quan va, quan luan, quan doan
van hien » van hieu, van tien

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

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