Perhaps you should try some spelling variations:
thanh trung » thanh tung
cong thuong » hang thuong
cong luong » nang luong, cong dong, cong cong
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
doc hieu » toc thieu, hoc thieu, hoc hien
toan cao » toan tap
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 - thanh trung cua ((cong luong) OR (cong thuong)) giao ((toan cao) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - thanh trung cua ((cong luong) OR (cong thuong)) giao ((toan cao) OR (toan ban))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu lang - thanh trung cua ((cong luong) OR (cong thuong)) giao ((toan cao) or (toan ban))*".