Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
luan chung » luan chinh
theo hieu » theo chieu, theo tieu, thien hieu
hieu lang » chieu sang, hieu quang, nhieu tang
cua chung » cua nhung, luat chung, cua cong
san toan » van toan, manh toan, xuan toan
dan toan » van toan, dan than, manh toan

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 lang - hanh trinh ((luan chung) or (cua chung)) cong ((san toan) OR (dan toan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo hieu lang - hanh trinh ((luan chung) OR (cua chung)) cong ((san toan) OR (dan toan)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo hieu lang - hanh trinh ((luan chung) or (cua chung)) cong ((san toan) OR (dan toan)) cao".
• Adding a wildcard symbol may retrieve word variants: theo hieu lang - hanh trinh ((luan chung) or (cua chung)) cong ((san toan) OR (dan toan)) cao*.