Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hanh trinh » canh tranh
quang dung » quang trung, ung dung, cuong dung
dung cong » dung trong
cong toan » cong tan, cong hoan, cong tuan
phan cau » phan cac, phan tu, phan lap
phan dau » phan tu, hang dau
ho hieu » ho chieu, hoi hieu, nho hieu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu quang - ((hanh trinh) OR (hanh chinh)) quang dung cong toan ((phan cau) OR (phan dau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu quang - ((hanh trinh) or (hanh chinh)) quang dung cong toan ((phan cau) OR (phan dau))~".
• Adding a wildcard symbol may retrieve word variants: ho hieu quang - ((hanh trinh) or (hanh chinh)) quang dung cong toan ((phan cau) OR (phan dau))*.