Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
hanh tang » hanh trang, anh tang, hanh mang
luan dang » luan nang, luan danh, luan dong
doc hieu » toc thieu, hoc thieu, hoc hien
cong van » cong vang, song van, cong tan
cong san » cong tac
toan ban » van ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu lang - ((hanh tang) or (canh tranh)) luan dang ((cong van) OR (cong san)) toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - ((hanh tang) OR (canh tranh)) luan dang ((cong van) OR (cong san)) toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu lang - ((hanh tang) or (canh tranh)) luan dang ((cong van) OR (cong san)) toan ban".
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - ((hanh tang) or (canh tranh)) luan dang ((cong van) OR (cong san)) toan ban*.