Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
manh tung » manh hung, thanh tung
doi hieu » doi chieu, doc hieu, doi hien
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
toan cao » toan ban, toan tap
tung va » trung va, tuong va, dung va

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi hieu lang - manh tung va nhung ((cong dan) or (cong san)) toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - manh tung va nhung ((cong dan) OR (cong san)) toan cao.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - manh tung va nhung ((cong dan) or (cong san)) toan cao*.