Perhaps you should try some spelling variations:
quang toan » quang tuan, quang tran, quang doan
hieu soat » hieu suat, hieu hoat, hieu luat
quang tan » quang tuan, quang tran, quang ban
dien hoat » dien hoa, dien hat, trien hoat
van hieu » cao hieu
van dien » van tien, van hien, van kien
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: (( trinh dung luan van hieu soat ) or ( tinh ((quang tan) OR (quang toan)) van dien hoat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung luan van hieu soat ) OR ( tinh ((quang tan) OR (quang toan)) van dien hoat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( trinh dung luan van hieu soat ) or ( tinh ((quang tan) OR (quang toan)) van dien hoat ))".
• Adding a wildcard symbol may retrieve word variants: (( trinh dung luan van hieu soat ) or ( tinh ((quang tan) OR (quang toan)) van dien hoat ))*.