Perhaps you should try some spelling variations:
thong doan » thong dan, trong doanh, thong hoang
hanh trang » thanh trung, hanh trinh, minh trang
hieu lang » chieu sang, hieu quang, nhieu tang
hoc hieu » hoc thieu, hoc hien, doc hieu
va thong » va thuong, va phuong, he thong
doan van » doan va, hoang van, luan van

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 - ((hanh trang) or (canh tranh)) va thong thong doan van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - ((hanh trang) OR (canh tranh)) va thong thong doan van ban.
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - ((hanh trang) or (canh tranh)) va thong thong doan van ban*.