Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, hieu manh
hanh trang » thanh trung, canh tranh, hanh trinh
nhung cong » dung cong, thong cong, hang cong
hieu xanh » chieu xanh, hieu manh, dieu hanh
trang va » tran van, hang va
dan toan » van toan, dan than, manh toan

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu xanh) OR (hieu nganh)) - hanh trang va nhung cong ((dan toan) or (thanh pho)) ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu xanh) OR (hieu nganh)) - hanh trang va nhung cong ((dan toan) OR (thanh pho)) ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu xanh) OR (hieu nganh)) - hanh trang va nhung cong ((dan toan) or (thanh pho)) ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu xanh) OR (hieu nganh)) - hanh trang va nhung cong ((dan toan) or (thanh pho)) ban*.