Perhaps you should try some spelling variations:
quang tuan » quang thanh, quan luan, quang cua
huong ltan » huong lan, huong loan, phuong loan
hieu suat » hieu luat
kien soat » kiem soat, bien soan, kien hoa
tuan van » luan van, tran van, tan van
ltan van » luan van, tan van, lan van
van kien » van tien, van hien, van chien
tinh » trinh, dinh, minh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh quang tuan van ((hieu suat) or (hieu qua)) ) or ( anh huong ltan van kien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang tuan van ((hieu suat) OR (hieu qua)) ) OR ( anh huong ltan van kien soat )).
• Adding a wildcard symbol may retrieve word variants: (( tinh quang tuan van ((hieu suat) or (hieu qua)) ) or ( anh huong ltan van kien soat ))*.