Perhaps you should try some spelling variations:
thuong cong » thong cong, thuong con, truong cong
thuong dong » phuong dong, tuong dong, chuong dong
hieu lang » chieu sang, hieu quang, nhieu tang
hoc hieu » hoc thieu, hoc hien, doc hieu
trung va » truong va, trang va, trung ha
ban than » ban thanh, van thanh, ban hang
than cau » toan cau, phan cau, than cap
tung va » tuong va, dung va, vung va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu lang - thanh ((tung va) OR (trung va)) ((thuong cong) or (thuong dong)) ban than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - thanh ((tung va) OR (trung va)) ((thuong cong) OR (thuong dong)) ban than cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - thanh ((tung va) OR (trung va)) ((thuong cong) or (thuong dong)) ban than cau".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - thanh ((tung va) OR (trung va)) ((thuong cong) or (thuong dong)) ban than cau*.