Perhaps you should try some spelling variations:
quang trong » quang truong, quang trung, quan trong
tinh luong » tinh huong, dinh luong, minh luong
luong luan » luong quan, luong xuan, cuong luan
hieu soat » hieu suat, hieu hoat, hieu luat
van hieu » cao hieu
van hien » van tien
va kiem » van kien

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh luong luan van hieu soat ) or ( tinh quang trong ((van hien) or (va kiem)) soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh luong luan van hieu soat ) OR ( tinh quang trong ((van hien) OR (va kiem)) soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh luong luan van hieu soat ) or ( tinh quang trong ((van hien) or (va kiem)) soat ))*.