Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
thanh tung » thanh cong
hoc bang » hoc bong, hoc tang, hoc dan
cong tac » cong ty
tac than » tac thanh, tam than, tac nhan
than cau » toan cau, phan cau, than cap
ho hieu » ho chieu, hoi hieu, nho hieu
hoc tan » hoc tang, hoc dan, hoc tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu quang - ((thanh trung) OR (thanh tung)) ((hoc bang) or (hoc tan)) cong tac than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu quang - ((thanh trung) OR (thanh tung)) ((hoc bang) OR (hoc tan)) cong tac than cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu quang - ((thanh trung) OR (thanh tung)) ((hoc bang) or (hoc tan)) cong tac than cau".
• Adding a wildcard symbol may retrieve word variants: ho hieu quang - ((thanh trung) OR (thanh tung)) ((hoc bang) or (hoc tan)) cong tac than cau*.