Perhaps you should try some spelling variations:
hanh tranh » hanh trinh, hanh trang, lanh tranh
theo hieu » theo chieu, theo tieu, thien hieu
hieu lang » chieu sang, hieu quang, nhieu tang
cua tong » cua cong, cua nong, cua song
cua dong » chua dong, cua cong, cua dang
cong san » cong tac
san toan » van toan, dan toan, manh toan
toan tap » toan ban

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