Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
trung xay » trung gay, trung tam, trung cap
trong xay » thong xay, trong cac, trong ca
doc hieu » toc thieu, hoc thieu, hoc hien
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
than cap » khan cap, thanh lap, thanh cac

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 - thanh ((trung xay) OR (trong xay)) dung ((cong dan) or (cong san)) than cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - thanh ((trung xay) OR (trong xay)) dung ((cong dan) OR (cong san)) than cap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu lang - thanh ((trung xay) OR (trong xay)) dung ((cong dan) or (cong san)) than cap".
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - thanh ((trung xay) OR (trong xay)) dung ((cong dan) or (cong san)) than cap*.