Perhaps you should try some spelling variations:
duong luan » dong luan, duong quan, duong xuan
quang tran » quang tuan, quang trung, quang thanh
hieu soat » hieu suat, hieu hoat, hieu luat
kiem soat » kiem toan
van hieu » cao hieu
tran van » luan van
van kiem » va kiem, van kien, van hien

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: (( dinh ((duong luan) OR (dung luan)) van hieu soat ) OR ( tinh quang tran van kiem soat ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( dinh ((duong luan) OR (dung luan)) van hieu soat ) or ( tinh quang tran van kiem soat ))~".
• Adding a wildcard symbol may retrieve word variants: (( dinh ((duong luan) OR (dung luan)) van hieu soat ) or ( tinh quang tran van kiem soat ))*.