Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
thanh tran » thanh trang, thanh toan, thanh tra
hieu quan » hieu qua, lieu quan, thien quan
tuan dung » tuan duong, tran dung, tan dung
cong tap » cuong tap, cong tac, cong tan
tap toan » tap doan, tap quan, bai toan
toan cau » toan cao, toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo ((hieu quang) OR (hieu quan)) - thanh tran ((tuan dung) or (tin dung)) cong tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((hieu quang) OR (hieu quan)) - thanh tran ((tuan dung) OR (tin dung)) cong tap toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((hieu quang) OR (hieu quan)) - thanh tran ((tuan dung) or (tin dung)) cong tap toan cau".
• Adding a wildcard symbol may retrieve word variants: theo ((hieu quang) OR (hieu quan)) - thanh tran ((tuan dung) or (tin dung)) cong tap toan cau*.