Perhaps you should try some spelling variations:
cong thanh » dong thanh, cong trinh, cong tan
cong luong » cong thuong, nang luong, cong dong
hieu lang » chieu sang, hieu quang, nhieu tang
doi hieu » doi chieu, doc hieu, doi hien
hanh ban » thanh ban, hang ban, hanh san
va thong » va thuong, va phuong, he thong
tuan cau » toan cau, quan cau, tuan cu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - hanh ban va thong ((cong thanh) OR (cong luong)) tuan cau~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - hanh ban va thong ((cong thanh) or (cong luong)) tuan cau*.