Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hanh tranh » canh tranh, hanh trinh, hanh trang
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, nhieu tang, hieu van
tranh cua » doanh cua, manh cua
cua thong » cua thuong, cua khong, cua tong
cong dan » cong san, cong tan, huong dan
dan than » dan chan, ban than, van than
than cao » toan cao, thai cao, than cap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoi ((hieu lang) or (hieu quang)) - hanh tranh cua thong cong dan than cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoi ((hieu lang) OR (hieu quang)) - hanh tranh cua thong cong dan than cao.
• Adding a wildcard symbol may retrieve word variants: hoi ((hieu lang) or (hieu quang)) - hanh tranh cua thong cong dan than cao*.