Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
dong cong » duong cong, dung cong, cong cong
dang cong » dung cong
cong cua » cong cu, dong cua, huong cua
toan cau » toan ban, toan tap, toan tai
toan cao » toan ban, toan tap
ho hieu » ho chieu, hoi hieu, nho hieu

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: ho hieu lang - thanh cong cua ((dong cong) OR (dang cong)) tac ((toan cau) OR (toan cao))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu lang - thanh cong cua ((dong cong) OR (dang cong)) tac ((toan cau) or (toan cao))~".
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - thanh cong cua ((dong cong) OR (dang cong)) tac ((toan cau) or (toan cao))*.