Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hanh tranh » canh tranh, hanh trinh, hanh trang
nhung cong » thong cong, hang cong, nhung don
hieu lang » chieu sang, nhieu tang, hieu van
tranh cua » doanh cua, manh cua
dung cong » dung trong
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 ((nhung cong) OR (dung 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 ((nhung cong) OR (dung cong)) dan than cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoi ((hieu lang) or (hieu quang)) - hanh tranh cua ((nhung cong) OR (dung cong)) dan than cao".
• Adding a wildcard symbol may retrieve word variants: hoi ((hieu lang) or (hieu quang)) - hanh tranh cua ((nhung cong) OR (dung cong)) dan than cao*.