Perhaps you should try some spelling variations:
quang quan » quang tuan, quang uan, quan quan
hieu soat » hieu suat, hieu hoat, hieu luat
tinh dang » tinh dung, binh dang, tinh sang
kiem soat » kiem toan
quan cau » quang cao, toan cau, quan ha
cau hieu » cao hieu, cau dieu, cau hien
quan van » luan van, quan va, quan doan

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 quan cau hieu soat ) OR ( tinh dang ((quan van) OR (quan luan)) kiem soat ))~.
• Adding a wildcard symbol may retrieve word variants: (( tinh quang quan cau hieu soat ) or ( tinh dang ((quan van) or (quan luan)) kiem soat ))*.