Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hanh trinh » canh tranh, hanh chinh
luan chung » luan chinh
qua nhung » quan nhung, cua nhung, qua chung
cong toan » cong tan, cong hoan, cong tuan
phan dau » phan tu, hang dau
ho hieu » ho chieu, hoi hieu, nho hieu
van dau » van dao

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 ((luan chung) OR (qua nhung)) cong toan ((van dau) OR (phan dau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu quang - hanh trinh ((luan chung) or (qua nhung)) cong toan ((van dau) OR (phan dau))~".
• Adding a wildcard symbol may retrieve word variants: ho hieu quang - hanh trinh ((luan chung) or (qua nhung)) cong toan ((van dau) OR (phan dau))*.